From Tafsir al-Maududi:
وَإِنْ خِفْتُمْ أَلَّا تُقْسِطُوا فِي الْيَتَامَىٰ فَانكِحُوا مَا طَابَ لَكُم مِّنَ النِّسَاءِ مَثْنَىٰ وَثُلَاثَ وَرُبَاعَ فَإِنْ خِفْتُمْ أَلَّا تَعْدِلُوا فَوَاحِدَةً أَوْ مَا مَلَكَتْ أَيْمَانُكُمْ ذَٰلِكَ أَدْنَىٰ أَلَّا تَعُولُوا
And if you be apprehensive that you will not be able to do justice to the orphans, you may marry two or three or four women whom you choose. But if you apprehend that you might not be able to do justice to them, then many only one wife, or marry those women who have fallen in your possession. This will be the better course to avoid injustice.
And if you be apprehensive that you will not be able to do justice to the orphans, you may marry two or three or four women whom you choose.
The commentators ascribe 3 meanings to this:
- Hadrat Aisha says that this was revealed to remedy an evil that was prevalent in the days of "Ignorance."
The guardians of the orphan girls used to marry them for their wealth and beauty, with the intention of keeping them under their power because they had no one to defend their cause; then they treated them unjustly without any fear. Therefore when they became Muslims, they had misgivings about marrying orphan girls. Accordingly, the Qur'an advised them to marry women of their choice other than orphan girls in their charge, if they feared that they would not be able to do justice to them. Verse 127 of this Surah also supports this comment.
- Hadrat Ibn Abbas and his disciple Ikrimah assert that this Commandment was given to eradicate an injustice that was prevalent at that time.
In pre-Islamic days, there was no limit to the number of wives and some people would marry even a dozen of them but when they could not meet the increasing expenses, they were forced to grab the property of their orphan nephews and other helpless relatives. Therefore, Allah restricted the maximum number of wives to four, and enjoined that this too, was subject to the condition that one should do justice to all of them.
- Sa'id ibn Jubair, Qatadah and some other commentators declare that this Command was given to safeguard the interests of wives.
They say that even before the advent of Islam, injustice to the orphans was looked upon with disfavor, but in regard to wives, it was different; they would marry as many as they liked and would treat them cruelly and unjustly without any fear of the society or pangs of conscience. Therefore Allah warned them that they should refrain from doing injustice to their wives as they did in the case of the orphans. Therefore they should not marry more than four wives and that too, only if they would do justice to them.
But if you apprehend that you might not be able to do justice to them, then marry only one wife.
The consensus of opinion of all the scholars of the Sharia is that this verse limits the number of wives and prohibits the keeping of more than four at one and the same time.
Ibn Kathir says in his tafsir:
Imam Ahmad recorded that Salim said that his father said that Ghilan bin Salamah Ath-Thaqafi had ten wives when he became Muslim, and the Prophet said to him, "Choose any four of them (and divorce the rest)." During the reign of Umar, Ghilan divorced his remaining wives and divided his money between his children. When Umar heard news of this, he said to Ghilan, "I think that the devil has conveyed to your heart the news of your imminent death, from what the devil hears during his eavesdropping. It may as well be that you will not remain alive but for a little longer. By Allah! You will take back your wives and your money, or I will take possession of this all and will order that your grave be stoned as is the case with the grave of Abu Righal (from Thamud, who was saved from their fate because he was in the Sacred Area. But, when he left it, he was tormented like they were)."
This verse restricts polygamy with the provision of justice to all the wives; therefore whoever abuses this permission without fulfilling the condition of justice and marries more wives than one tries to deceive Allah. The courts of an Islamic State are, therefore, empowered to enforce justice in order to rectify the wrong done to a wife or wives. At the same time it is absolutely wrong to conclude from the proviso of justice, attached to this Commandment, that this verse was really meant to abolish polygamy. This is not the view of the Qur'an, but of those Muslims who have been overawed by the Christians of the West. They say that the Qur'an is also against polygamy but it did trot abolish it directly because it did not consider it expedient at the time for the custom had become very common. Instead of this, it allows polygamy provided that justice is done to all the wives. As this condition is most difficult to fulfill, the recommendation is towards monogamy. Obviously, this way of thinking is the result of mental slavery, because polygamy in itself is not an evil for in some cases it becomes a real cultural and moral necessity. There are Borne people, who, even if they wished, cannot remain content with one wife. Polygamy comes to their rescue and saves them and the society in general from the harms of unlicensed sexual indulgences. That is why the Qur'an allows polygamy to such people with the explicit condition of doing justice to all the wives.
Or marry those women who have fallen in your possession.
"Those women" are slave girls captured in war and distributed among the people by the government.
It may either mean: "If you cannot bear the expenses of a free woman, you may marry a slave girl as permitted in.v. 25," or it may mean: "If you need more wives than one but are afraid that you might not be able to do justice to your wives from among the free people, you may turn to slave girls because in that case you will be burdened with less responsibilities.
In conclusion, the whole verse is saying that the orphans at that time were treated unjustly but then the people at that time refrained from it and similarly, those people and us should refrain from treating women with injustice (marrying a lot of women). The verse gives a limit to up to 4 wives at one time if a man can treat each of them equally with justice and not favour one of them as the last part of the verse says:
This will be the better course to avoid injustice.
but since this is difficult to fulfil, you should marry 1 wife or slave girls captured in war.
Tafsir Ibn Kathir