Ruling on Plural Marriage
Question

What is the ruling on plural marriage?
Praise be to Allah.Ruling on plural marriage
Allah has allowed men to have more than one wife, as He says (interpretation of the meaning): 
“And if you fear that you shall not be able to deal justly with the orphan girls then marry (other) women of your choice, two, or three, or four; but if you fear that you shall not be able to deal justly (with them), then only one or (slaves) that your right hands possess. This way you are less likely to commit injustice.” [An-Nisa’ 4:3]
This clearly shows that plural marriage is permissible, and that according to Islamic Shari`ah a man may marry one, two, three or four wives, but it is not permissible for him to marry more than four . This is the view of the scholars of Tafsir and jurists; the Muslims are unanimously agreed on this point and there is no difference of opinion. 
Conditions of plural marriage
It should be noted that there are conditions attached to plural marriage : 

Justice and fairness. 

Allah says (interpretation of the meaning): “but if you fear that you shall not be able to deal justly (with them), then only one” [An-Nisa’ 4:3]. This verse shows that justice is a condition of plural marriage being permissible. If a man fears that he will not be able to treat his wives fairly if he marries more than one, then it is forbidden for him to marry more than one. What is meant by justice here is treating all wives equally with regard to spending, clothing, staying overnight and other material matters which are within his ability to control. 
With regard to justice and equal treatment in the area of love, he is not held accountable for that, and it is not required of him because it is not possible to control it. This is what is meant by the words of Allah (interpretation of the meaning): 
“You will never be able to do perfect justice between wives even if it is your ardent desire.” [An-Nisa’ 4:129] i.e., with regard to love of the heart. 

Being able to afford spending on plural wives . 

The evidence for this is the verse in which Allah says (interpretation of the meaning): 
“And let those who find not the financial means for marriage keep themselves chaste, until Allah enriches them of His Bounty.” [An-Noor 24:33] 
In these verses, Allah commands the one who is able to get married but cannot afford it to remain chaste. One of the reasons for not being able to afford to get married is not having enough to pay the Mahr (dowry given to the wife) or not being able to spend on one’s wife. (Al-Mufasal fi Ahkam Al-Mar’ah, vol. 6, p. 286) 
Some scholars view that plural marriage is better than restricting oneself to one wife. Shaykh Ibn Baz (may Allah have mercy on him) was asked: Is the basic principle concerning marriage plural marriage or marriage to one wife? 
He replied: 
“The basic principle in Shari`ah is plural marriage for those who can afford it, if there is no fear of injustice, because of the many interests that are served by that, such as keeping himself and those whom he marries chaste, kind treatment of them, producing lots of children and increasing the numbers of the Ummah and the numbers of those who worship Allah alone. This is indicated by the words of Allah (interpretation of the meaning): 
“And if you fear that you shall not be able to deal justly with the orphan girls then marry (other) women of your choice, two or three, or four; but if you fear that you shall not be able to deal justly (with them), then only one or (slaves) that your right hands possess. This way you are less likely to commit injustice.” [An-Nisa’ 4:3]
And because the Prophet (peace and blessings of Allah be upon him) married more than one wife , and Allah says (interpretation of the meaning):
 “Indeed in the Messenger of Allah (Muhammad) you have a good example to follow.” [Al-Ahzab 33:21] 
One of the companions of the Prophet (peace and blessings of Allah be upon him) said, “As for me, I will not eat meat,” and another said, “As for me I will pray and never sleep”; another said, “As for me I will fast and never break my fast,” and another said: “As for me, I will never marry women.” When news of that reached him, the Prophet (peace and blessings of Allah be upon him) addressed these people. He praised Allah then he said: “You are the ones who said such and such. As for me, by Allah, I fear Allah more than you do, but I fast and I break my fast, I pray and I sleep, and I marry women. Whoever turns away from my Sunnah has nothing to do with me.” These great words of the Prophet (peace and blessings of Allah be upon him) include both marriage to one woman and plural marriage.” (Majallat Al-Balagh, issue no. 1015; Fatawa `Ulama Al-Balad Al-Haram, p. 386) 
And Allah knows best.