Reasons why a person who has recently become righteous may backslide, and guidance for one who wants to seek knowledge
Question

I am looking for advice for someone who has recently become committed; what should he do so that he will not backslide? And I am looking for advice on what books one should start reading after the Qur’aan.
Praise be to Allah.Allaah rejoices over the repentance of His slave even though He is the One Who helps this penitent to repent, and He is not harmed by people’s sins, no matter how many they are. This is due to His great mercy towards His creation, and His great bounty. What we advise our brothers who are adhering to guidance and seeking to do good is: 
1 – Praise Allaah and thank Him with sincerity for having guided them to the path of Paradise. They should understand that were it not for Allaah, they would not have been guided or prayed. As well as praising and thanking Allaah, they also need to pray to Allaah to make them steadfast in adhering to Islam and truth, for hearts are in the hand of Allaah and He turns them as He wills. The Prophet (peace and blessings of Allaah be upon him) used to say in his du’aa’: Yaa muqallib al-quloob thabbit qalbi ala deenaka, Yaa musarrif al-quloob, asrif qalbi ila taa’atika (O Controller of the hearts, make my heart adhere firmly to Your religion, O Director of the hearts, direct my heart to obey You). And we are in greater need of this du’aa’ than him, (peace and blessings of Allaah be upon him). 
2 – Adhering to obedience of Allaah by doing obligatory duties and being keen to do more in order to draw closer to Allaah after doing the obligatory duties, by doing sunnahs, so as to attain the love of Allaah, for whomever Allaah loves, He will make him steadfast in following the path and will increase him in guidance. 
It was narrated that Abu Hurayrah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whosoever shows enmity to someone devoted to Me, I shall be at war with him. My servant draws not near to Me with anything more loved by Me than thereligious duties I have enjoined upon him, and My servant continues to draw near to Me with supererogatory works so that I shall love him. When I love him I am his hearing with which he hears, his seeing with which he sees, his hand with whichhe strikes and his foot with which he walks. Were he to ask [something] of Me, I would surely give it to him, and were he to ask Me for refuge, I would surely grant him it.” Narrated by al-Bukhaari (6137). 
3 – Seeking the pleasure of Allaah and longing to meet Him, and not being distracted by this world or by its permissible things or pleasures. This righteous person’s motive to obey Allaah should be sublime and not worldly, and his aim should be to attain eternal happiness in an abode where no one grows old or falls sick, which is Paradise. 
4 – He should seek knowledge, starting with memorization of the Book of Allaah, then studying the Sunnah and reading books of salafi ‘aqeedah, Tawheed and fiqh, because the more a Muslim learns his religion, the more firmly he will adhere to it, and one of the greatest causes of backsliding and falling from the path is ignorance and lack of knowledge of Islam. 
5 – He should be keen to find righteous companions and give up bad companions, especially those who were with him on his path of negligence before, lest they be a cause of him going back to his old ways. The Prophet (peace and blessings of Allaah be upon him) likened a good friend to the carrier of musk, for he will either give you some or you will notice a good smell from him; and he likened the bad friend to the one who works the bellows, for he will either burn your clothes or you will notice a bad smell from him. This is how it is with good friends and bad friends. The former will either guide you towards what is good, or you will see good in him and his attitude and behaviour, but the bad friend will either guide you towards sin and you will do it, or he will do it himself and you will not see anything from him but evil and encouragement to commit evil actions. So you should be keen to seek good company and avoid bad company. 
6 – Beware of sins, both minor and major, for most fires start due to minor causes and one sin leads to another. If the heart is darkened and blackened because of sin, it will no longer be a heart that is alive and recognizes good as good and evil as evil. So beware, beware of sin. It was narrated from ‘Abd-Allaah ibn Mas’ood (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Beware of trivial sins, for they will accumulate until they destroy a man.” And the Messenger of Allaah (peace and blessings of Allaah be upon him) gave an example, likening them to people who stopped to camp in the wilderness, and they wanted to prepare some food, so one man went and brought a stick, and another man brought a stick, until they had gathered a huge pile and lit a fire, and whatever they put in the pot was cooked as a result.
Narrated by Ahmad (37/467); classed as hasan by Shu’aub al-Arna’oot and as saheeh by al-Albaani. 
7 – Beware of the fitnah (temptation) of wealth. The one whom Allaah has blessed with wealth should use that wealth to help him obey Allaah and spend it in ways that please Allaah, such as building mosques, printing books, recording tapes and distributing pamphlets. He should be keen to perform Hajj and ‘umrah, and beware of going to extremes with regard to permissible things or spending it on haraam things, for wealth may be a cause of a person being tempted  away from his religious commitment. Allaah indeed spoke the truth when He said (interpretation of the meaning): 
“Your wealth and your children are only a trial, whereas Allaah! With Him is a great reward (Paradise)”
[al-Taghaabun 64:15]
8 – The one who has been guided must fill his heart with faith, for if the heart is sound the whole body will be sound, but if it is corrupt the whole body will be corrupt. So he should strive to read Qur’aan and do a lot of acts of worship.  
9 – One of the reasons why a person backslides may be that he does not have a wife, so he should be keen to get married and form a family, and he should be keen to discipline them and teach them. Being single may be a cause of falling into sin, thinking of desires, staying up late at night a great deal, not living a serious life and being content with a life of relaxation and laziness. 
10 – Finally, the one who has been recently guided needs to be moderate in performing acts of worship and be wise in calling people to Islam, for some of those whom Allaah guides to the path of truth make it hard on themselves with regard to doing acts of worship, and they are hard on others when they call them and remind them. Perhaps this is a reason why they backslide. So he should be keen to be moderate and wise and gentle, and he should strive to consult people of knowledge and seek their advice, for there is a great deal of good in that for him.
It was narrated that ‘Abd-Allaah ibn ‘Amr (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Every deed has a period of enthusiasm, and every period of enthusiasm is followed by a slackening off. If a person’s enthusiasm is for my Sunnah, then he has succeeded, but whoever chooses something else when he slackens off is doomed.”
Narrated by Ibn Hibbaan in his Saheeh (1/187); classed as saheeh by al-Albaani in Saheeh al-Targheeb, 56. 
See the commentary on this hadeeth and more details on this point in the answer to question no. 70314. 
We ask Allaah to make us steadfast in adhering to the truth and to make us sincere in word and deed. 
Secondly: 
With regard to the seeker of knowledge who is just beginning, it is essential to give him advice with regard to the pursuit of knowledge so that he will be rewarded for his seeking and so that it will not be a burden on him. 
1. Be sincere in your intention to seek knowledge. Remember that seeking knowledge is an act of worship and that Allaah does not accept any act of worship but that which is done sincerely for His sake. So do not seek knowledge for the sake of fame, status, wealth, arguing with fools or debating with scholars, rather seek it sincerely for the sake of Allaah, in obedience to the command of Allaah and so as to remove ignorance from yourself and others.
2. Be patient in seeking knowledge and do not be hasty, for the path is long and hard, and “whoever works hard at the beginning will reach his target.”  
3. Act upon what you learn, for knowledge calls for action, but if it meets with no response, it will move on.
4. Start with easy issues of knowledge before difficult ones. Do not start with Fath al-Baari or al-Majmoo’ or al-Muhalla, rather start with small texts until you are ready for the big ones.
5. Strive to study with a Shaykh whose religious commitment and knowledge can be trusted; if that is not possible then study with a seeker of knowledge who is ahead of you on the path.
6. Use a variety of methods of seeking knowledge so that you will not get bored, such as reading, listening and watching.
7. Try to acquire books with commentaries by trustworthy scholars.
8. Do not start with controversial books before you have mastered the basics of evidence from the Qur’aan and saheeh Sunnah.
9. Be humble towards Allaah and beware of two dangers: arrogance, and destructive envy (hasad). The salaf would listen to those who were older than them in order to learn good manners, and they would listen to those who were younger than them in order to learn humility, and those who were like them in order to remove the disease of envy from their hearts.
10. Do not be in a hurry to issue fatwas, and strive to study hard, summarize what you have read and write down new ideas you learn so that you can revise them; strive to teach the ignorant things that will benefit them. Allaah says (interpretation of the meaning): “and spend out of what we have provided for them” [al-Baqarah 2:3].
See also the answer to question no. 10324 for information on the etiquette of seeking knowledge. 
Thirdly: 
With regard to the books with which one should start after reading the Book of Allaah and which one should try to memorize, there are many. We have mentioned the most important of trustworthy books and what is appropriate at every stage of seeking knowledge, in the answers to question no. 14082 and 20191. 
We should also point out that on our site under the heading of Knowledge and Da’wah/ Knowledge there are many answers from which the seeker of knowledge may learn about etiquette, rulings and advice. 
We ask Allaah to guide you always and to make it easy for you to acquire beneficial knowledge and do righteous deeds, for the one whom Allaah guides is truly guided and the one whom He sends astray can never be guided. 
And Allaah knows best.