Slavery in Islam
Question

I often hear Christian missionaries criticizing Islam and accusing it because Islam permitted slavery, and saying that this is a transgression against man’s freedom and rights. How can we respond to these people?
Praise be to Allah.Slavery in other religions
Discussing slavery and asking questions about it on the part of those who promote Christianity and try to divert people from following the religion of Islam is something that annoys the wise person and makes him point the finger of accusation towards the ulterior motives that lie behind these questions.  
That is because slavery is well established in Judaism and Christianity, where it has taken unjust forms. They have many books which discuss that in detail and condone it. Therefore it makes you wonder: how can these churchmen call people to Christianity when Christianity condones and legitimizes slavery? 
In other words: how can they stir up an issue when they themselves are up to their necks in it?! 
The issue of slavery is completely different when discussed from the angles of Christianity and Islam, and when compared with the situation that prevailed at the advent of Islam. 
Hence we must discuss this topic in some detail with reference to what is said in Judaism, Christianity and contemporary culture on this matter, then we will speak of slavery in Islam. 
Many lies have been fabricated about Islam on this topic, at a time when criminals with lengthy track records are safe and nobody points a finger at them. 
Slavery in Islam 
Islam affirms that Allah, may He be glorified and exalted, created man fully accountable, and enjoined duties upon him, to which reward and punishment are connected on the basis of man’s free will and choice. 
No human being has the right to restrict this freedom or take away that choice unlawfully; whoever dares to do that is a wrongdoer and oppressor.  
Why does Islam permit slavery?
This is one of the basic principles of Islam. When the question is asked: why does Islam permit slavery? We reply emphatically and without shame that slavery is permitted in Islam, but we should examine the matter with fairness and with the aim of seeking the truth, and we should examine the details of the rulings on slavery in Islam, with regard to the sources and reasons for it, and how to deal with the slave and how his rights and duties are equal to those of the free man, and the ways in which he may earn his freedom, of which there are many in shari’ah, whilst also taking into consideration the new types of slavery in this world which is pretending to be civilized, modern and progressive. 
Slavery before Islam
When Islam came, there were many causes of slavery, such as warfare, debt (where if the debtor could not pay off his debt, he became a slave), kidnapping and raids, and poverty and need. 
Slavery did not spread in this appalling manner throughout all continents except by means of kidnapping; rather the main source of slaves in Europe and America in later centuries was this method. 
The texts of Islam took a strong stance against this. It says in a hadith qudsi: “Allah, may He be exalted, said: ‘There are three whose opponent I will be on the Day of Resurrection, and whomever I oppose, I will defeat … A man who sold a free man and consumed his price.’” (Narrated by al-Bukhari, 2227)
It is worth pointing out that you do not find any text in the Quran or Sunnah which enjoins taking others as slaves, whereas there are dozens of texts in the Quran and the ahadith of the Messenger (peace and blessings of Allah be upon him) which call for manumitting slaves and freeing them. 
Sources of slaves at the time of the advent of Islam
There were many sources of slaves at the time of the advent of Islam, whereas the means of manumitting them were virtually nil. Islam changed the way in which slavery was dealt with; it created many new ways of liberating slaves, blocked many ways of enslaving people, and established guidelines which blocked these means. 
Islam limited the sources of slaves that existed before the beginning of the Prophet’s mission to one way only: enslavement through war which was imposed on non-Muslim prisoners-of-war and on their womenfolk and children. 
Shaykh al-Shanqiti (may Allah have mercy on him) said: 
“The reason for slavery is kufr and fighting against Allah and His Messenger. When Allah enables the Muslim mujahidin who are offering their souls and their wealth, and fighting with all their strength and with what Allah has given them to make the word of Allah supreme over the kuffar, then He makes them their property by means of slavery unless the ruler chooses to free them for nothing or for a ransom, if that serves the interests of the Muslims.” (Adwa al-Bayan, 3/387)
He also said: 
“If it is said: If the slave becomes Muslim then why keep him as a slave, when the reason for slavery is kufr and fighting against Allah and His Messenger, so this reason no longer applies? 
The answer is that the well-known principle among the scholars and all wise people, which is that the previously established right cannot be erased by a right that is established later, and that what came first takes precedence, is obvious. 
When the Muslims captured non-Muslims, their right to possession was affirmed by the law of the Creator of all, Who is All Wise and All Knowing. So this right is confirmed and established. Then if the slave became Muslim after that, his right to escape slavery by embracing Islam was superseded by the mujahid’s prior right to take possession of him before he became Muslim, and it would be unjust and unfair to annul the prior right because of a subsequent right, as is well known to all wise people. 
Yes, it is good for the master to free the slave if he becomes Muslim. The Lawgiver enjoined and encouraged that, and opened many doors to it. Glory be to the Most Wise, the All Knowing. “And the Word of your Lord has been fulfilled in truth and in justice. None can change His Words. And He is the All-Hearer, the All-Knower” [al-An’am 6:115]. 
“in truth” means in what He tells us, and “in justice” means in His rulings. 
Undoubtedly this justice refers to owning slaves and other rulings of the Quran. 
How many people criticize something sound when their problem is their own misunderstanding.” (Adwa al-Bayan, 3/389)
Capture of prisoners during war was the most common way of acquiring slaves. Prisoners would inevitably be captured during any war, and the prevalent custom at that time was that prisoners had no protection or rights; they would either be killed or enslaved. But Islam brought two more options: unconditional release or ransom. Allah says (interpretation of the meaning): “Thereafter (is the time) either for generosity (i.e. free them without ransom), or ransom (according to what benefits Islam)” [Muhammad 47:4]. During the battle of Badr the Prophet (peace and blessings of Allah be upon him) accepted ransoms from the mushrik prisoners of war and let them go, and the Messenger (peace and blessings of Allah be upon him) let many of the prisoners go for free, releasing them with no ransom. During the conquest of Makkah it was said to the people of Makkah: “Go, for you are free.” 
During the campaign of Banu’l-Mustaliq, the Messenger (peace and blessings of Allah be upon him) married a female prisoner from the defeated tribe so as to raise her status, as she was the daughter of one of their leaders, namely the Mother of the Believers Juwayriyah bint al-Harith (may Allah be pleased with her). Then the Muslims let all of these prisoners go. 
Islam is not thirsty for the blood of prisoners, nor is it eager to enslave them. 
Thus we may understand the limited ways that can lead to slavery. Islam did not abolish it altogether, because the kafir prisoner who was opposed to truth and justice was a wrongdoer, or was a supporter of wrongdoing or was a tool in the execution or approval of wrongdoing. Letting him go free would give him the opportunity to spread wrongdoing and aggression against others and to oppose the truth and prevent it reaching people.  
Freedom is a basic human right which cannot be taken away from a person except for a reason. When Islam accepted slavery within the limits that we have described, it put restrictions on the man who exploits his freedom in the worst possible way. If he was taken prisoner in a war of aggression in which he was defeated, then the proper conduct is to keep him in reasonable conditions throughout his detention. 
Despite all that, Islam offers many opportunities to restore freedom to him and people like him. 
How Islam treated slaves 
The principle of dealing with slaves in Islam is a combination of justice, kindness and compassion. 
One of the means of liberating slaves is allocating a portion of zakah funds to freeing slaves; the expiation for accidental killing, zihar (a jahili form of divorce that is forbidden), breaking vows and having intercourse during the day in Ramadan, is to free a slave. In addition to that, Muslims are also encouraged in general terms to free slaves for the sake of Allah. 
This is a brief summary of some of the principles of dealing with slaves in a just and kind manner: 
1. Guaranteeing them food and clothing like that of their masters. 
Abu Dharr (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “They are your brothers whom Allah has put under your authority, so if Allah has put a person’s brother under his authority, let him feed him from what he eats and clothe him from what he wears, and let him not overburden him with work, and if he does overburden him with work, then let him help him.” Narrated by al-Bukhari (6050). 
2. Preserving their dignity 
Abu Hurayrah (may Allah be pleased with him) said: I heard Abu’l-Qasim (peace and blessings of Allah be upon him) say: “Whoever accuses his slave when he is innocent of what he says will be flogged on the Day of Resurrection, unless he is as he said.” (Narrated by al-Bukhari, 6858) 
Ibn ‘Umar (may Allah be pleased with him) manumitted a slave of his, then he picked up a stick or something from the ground and said: There is no more reward in it than the equivalent of this, but I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: “Whoever slaps his slave or beats him, his expiation is to manumit him.” (Narrated by Muslim, 1657) 
3. Being fair towards slaves and treating them kindly 
‘Uthman ibn ‘Affan tweaked the ear of a slave of his when he did something wrong, then he said to him after that: Come and tweak my ear in retaliation. The slave refused but he insisted, so he started to tweak it slightly, and he said to him: Do it strongly, for I cannot bear the punishment on the Day of Resurrection. The slave said: Like that, O my master? The Day that you fear I fear also. 
When ‘Abd al-Rahman ibn ‘Awf (may Allah be pleased with him) walked among his slaves, no one could tell him apart from them, because he did not walk ahead of them, and he did not wear anything different from what they wore. 
One day ‘Umar ibn al-Khattab passed by and saw some slaves standing and not eating with their master. He got angry and said to their master: What is wrong with people who are selfish towards their servants? Then he called the servants and they ate with them. 
A man entered upon Salman (may Allah be pleased with him) and found him making dough – and he was a governor. He said to him: O Abu ‘Abd-Allah, what is this? He said: We have sent our servant on an errand and we do not want to give him two jobs at once. 
4. There is nothing wrong with slaves having precedence over free men in some matters with regard to any religious or worldly matters in which he excels over him. For example, it is valid for a slave to lead the prayer. ‘Aishah, the Mother of the Believers, had a slave who would lead her in prayer. Indeed the Muslims have been commanded to hear and obey even if a slave is appointed in charge of their affairs. 
5. A slave may buy himself from his master and be free. 
If a person is enslaved for some reason but then it becomes apparent that he has given up his wrongdoing and forgotten his past, and he has become a man who shuns evil and seeks to do good, is it permissible to respond to his request to let him go free? Islam says yes, and there are some fuqaha who say that this is obligatory and some who say that it is mustahabb. 
This is what is called a mukatabah or contract of manumission between the slave and his master. Allah says (interpretation of the meaning): 
“And such of your slaves as seek a writing (of emancipation), give them such writing, if you find that there is good and honesty in them. And give them something (yourselves) out of the wealth of Allah which He has bestowed upon you.” [al-Nur 24:33]
This is how Islam treats slaves justly and kindly. 
One of the results of these guidelines is that in many cases, the slave would become a friend of his master; in some cases the master would regard him as a son. Sa’d ibn Hashim al-Khalidi said, describing a slave of his: 
“He is not a slave, rather he is a son whom [Allah] has put under my care.
He has supported me with his good service; he is my hands and my arms.” 
Another result of the Muslims treating slaves in this manner is that the slaves became part of Muslim families as if they were also family members.  
Gustave le Bon says in Hadarat al-‘Arab (Arab Civilization) (p. 459-460): 
“What I sincerely believe is that slavery among the Muslims is better than slavery among any other people, and that the situation of slaves in the east is better than that of servants in Europe, and that slaves in the east are part of the family. Slaves who wanted to be free could attain freedom by expressing their wish. But despite that, they did not resort to exercising this right.”
How did non-Muslims treat slaves? 
Attitude of the Jews towards slaves
According to the Jews, mankind is divided into two groups: the Israelites form one group and all of mankind is another group.  
As for the Israelites, it is permissible to enslave some of them, according to specific teachings contained in the Old Testament. 
As for people other than the Israelites, they are a low-class race according to the Jews, who may be enslaved via domination and subjugation, because they are people who are doomed to humiliation by the heavenly decree from eternity. It says in Exodus 21:2-6: 
“If you buy a Hebrew servant, he is to serve you for six years. But in the seventh year, he shall go free, without paying anything.
3 If he comes alone, he is to go free alone; but if he has a wife when he comes, she is to go with him.
4 If his master gives him a wife and she bears him sons or daughters, the woman and her children shall belong to her master, and only the man shall go free.
 5 But if the servant declares, 'I love my master and my wife and children and do not want to go free,'
6 then his master must take him before the judges. He shall take him to the door or the doorpost and pierce his ear with an awl. Then he will be his servant for life” 
As for enslaving non-Hebrews, this is done by taking them captive or overpowering them, because they believe that their race is superior to others, and they try to find a justification for that slavery in their distorted Torah. So they say that Ham the son of Noah – who was the father of Canaan – angered his father, because Noah was drunk one day and became naked as he was sleeping in his tent, and Ham saw him like that. When Noah found out about that after he woke up, he got angry and he cursed his progeny who were descendents of Canaan, and he said – according to the Book of Genesis 9:25-26): “Cursed be Canaan! The lowest of slaves will he be to his brothers.’ He also said, ‘Blessed be the LORD, the God of Shem! May Canaan be the slave of Shem.’” 
In the same chapter (v. 27) it says: “May God extend the territory of Japheth; may Japheth live in the tents of Shem, and may Canaan be his [or their] slave”. 
In the Book of Deuteronomy 20:10-14, it says: 
“When you march up to attack a city, make its people an offer of peace.
11 If they accept and open their gates, all the people in it shall be subject to forced labor and shall work for you.
12 If they refuse to make peace and they engage you in battle, lay siege to that city.
13 When the LORD your God delivers it into your hand, put to the sword all the men in it.
14 As for the women, the children, the livestock and everything else in the city, you may take these as plunder for yourselves” 
Attitude of the Christians towards slaves
Christianity confirmed slavery as it had been affirmed beforehand by Judaism. There is no text in the Gospels that prohibits or denounces slavery. It is remarkable that the historian William Muir criticized our Prophet Muhammad (peace and blessings of Allah be upon him) for not immediately abolishing slavery, whilst overlooking the attitude of the Gospels concerning slavery, as there is no report from the Messiah, or from the Disciples, or from the churches concerning this issue. 
Rather, in his Epistles, Paul advised that slaves should be loyal to their masters, as he says in his Epistle to the Ephesians, where he enjoins slaves to obey their masters as they would obey the Messiah: 
“5 Slaves, obey your earthly masters with respect and fear, and with sincerity of heart, just as you would obey Christ.
6 Obey them not only to win their favor when their eye is on you, but like slaves of Christ, doing the will of God from your heart.
7 Serve wholeheartedly, as if you were serving the Lord, not men,
8 because you know that the Lord will reward everyone for whatever good he does, whether he is slave or free.” (Ephesians 6:5-9). 
In Grand Larousse encyclopédique, it says: 
“It comes as no surprise that slavery has continued among Christians until today; the official representatives of the faith have affirmed its validity and accepted its legitimacy. 
… to sum up: the Christian religion approved fully of slavery and still does so today. It is very difficult for anyone to prove that Christianity strove to abolish slavery. 
The saints affirmed that nature makes some people slaves. 
Churchmen did not prevent slavery or oppose it; rather they supported it, to such an extent that the philosopher saint Thomas Aquinas supported the philosophical view that agreed with the view of religious leaders, and he did not object to slavery, rather he praised it because – according to the view of Aristotle – it is one of the conditions in which some people are created naturally, and it does not contradict faith for a man to be content with the lowest position in life.” Haqaiq al-Islam by al-‘Aqqad, p. 215) 
In the Dictionary of the Bible by Dr. George Yousuf it says: 
“Christianity did not object to slavery for political or economic reasons, and it did not urge believers to oppose their generation’s views with regard to slavery, or even debate it, and it did not say anything against the rights of slave owners or motivate the slaves to seek independence; it did not discuss the harm or harshness of slavery and it did not enjoin the immediate release of slaves.  
It did not change anything in the nature of the relationship between master and slave; on the contrary, it affirmed the rights and duties of both parties. 
Contemporary Europe and slavery 
It is the reader’s right, in this era of advancement and progress, to ask questions about the pioneers of this progress and the numbers of people who died because of the way in which they were hunted, and who died on their way to the coast where the ships of the English Company and others would wait, then the rest died due to changes in climate. Approximately 4% died as they were being loaded onto the ships, and 12 % during the journey, let alone those who died in the colonies. 
The slave trade continued at the hands of English companies that obtained the right of monopoly with the permission of the British government, then gave free rein to British subjects to enslave people. Some experts estimate that the total number of people seized by the British during slavery and exiled to the colonies between 1680 and 1786 CE was around 2,130,000. 
When Europe made contact with Black Africa, this contact led to human misery during which the black people of that continent were faced with a major calamity that lasted for five centuries. The states of Europe came up with evil ways of kidnapping these people and bringing them to their lands to serve as fuel for their revival, where they burdened them with more work than they could bear. When America was discovered, the calamity increased and they became slaves in two continents instead of just one. 
The Encyclopaedia Britannica says (2/779) on the topic of slavery: 
“Hunting slaves in the villages that were surrounded by the jungle was done by lighting fires in the straw of which the corrals surrounding the villages were made, then when the villagers fled to open land, the British hunted them down with whatever means they had at their disposal.”  
During the period from 1661 to 1774, for every million Black Africans who reached the Americas, a further nine million died during the hunting, loading and transportation. In other words, only one tenth of those who were hunted survived and actually reached the Americas, where they found no rest or relief, rather they were subjected to hard labour and torture. 
At that time, they had laws which any wise person would be ashamed of. 
Among these evil laws were those which said that any slave who transgressed against his master was to be killed, and any slave who ran away was to have his hands and feet cut off, and he was to be branded with hot iron; if he ran away again, he was to be killed. How could he run away if his hands and feet had been cut off?! 
It was forbidden for a black man to become educated, and the jobs of whites were forbidden to coloureds. 
In America, if seven black people gathered together, that was regarded as a crime, and if a white man passed by them it was permissible for him to spit at them and give them twenty lashes. 
Another law stated that the blacks had no soul and that they possessed no smartness, intelligence or willpower, and that life existed only in their arms. 
To sum up, with regard to his duties and service to his master, the slave was regarded as sane, responsible and punishable if he fell short, but with regard to his rights, he had no soul and no being, and he was not more than a strong pair of arms! 
Finally, after many centuries of enslavement and oppression, there came the protocol to abolish slavery and strive to put an end to it, in a resolution issued by the United Nations in 1953 CE. 
Hence their consciences did not awaken until the last century, after they had built their civilization on the corpses of free men whom they had enslaved unlawfully. What fair-minded person can compare this with the teachings of Islam, which came fourteen hundred years ago? It seems that accusing Islam with regard to this topic is like the saying, “She accused me of her problem then walked away.” 
And Allah knows best. 
For more, please see these answers: 5707 , 128160 , 13202 , 13737 , 5157 , 20085 , and 13241 .
References:

Shubahat Hawl al-Islam by Muhammad Qutub; 
Talbis Mardud fi Qadaya Hayyah by Shaykh Dr. Salih ibn Humayd, the Imam of the Haram in Makkah.