Tafsir of Al-Mumtahanah 60:10-11

{If the believing women come to you} He called them "believing" because they affirmed with their tongues and spoke the word of testimony, and nothing appeared from them that contradicted that. Or, it is because they were on the verge of confirming their faith through the test.

{So test them} Try them by having them swear oaths and by observing signs, so that the sincerity of their faith may prevail in your estimations. The Messenger of Allah (ﷺ) used to say to the woman being tested: "By Allah, besides whom there is no god, you have not left out of hatred for your husband; by Allah, you have not left out of a desire to move from one land to another; by Allah, you have not left out of a desire for worldly gain; by Allah, you have not left out except out of love for Allah and His Messenger."

{Allah is most knowing of their faith} He knows more than you do, because you cannot attain a level of knowledge regarding them that brings peace to your souls, even if you make them swear and examine their circumstances. With Allah lies the true knowledge of it.

{Then if you know them to be believers} With the knowledge that is within your capacity—which is the predominant assumption based on oaths and the appearance of signs—{do not return them to the disbelievers}. Do not send them back to their polytheist husbands, for there is no marital validity between a believing woman and a polytheist.

{And give them [the husbands] what they have spent} Give their husbands the equivalent of the dowries they paid for them. This is because the Treaty of Hudaybiyyah stipulated that whoever came from Mecca to the Muslims should be returned, and whoever went from the Muslims to Mecca should not be returned. When Subay'ah bint al-Harith al-Aslamiyyah came as a Muslim, her husband followed her and demanded her return based on the treaty. This verse was revealed to clarify that the condition applied only to men, not women.

Regarding the term "Knowledge" and "Faith" If you ask: How can he call "assumption" (zann) "knowledge" in the phrase {if you know them}? I say: It is an indication that predominant assumption, and what is reached through legal reasoning (ijtihad) and analogy, functions in the place of knowledge, and its practitioner is not included in the prohibition: {Do not pursue that of which you have no knowledge} (Al-Isra: 36).

{And do not hold onto the bonds of disbelieving women} "Bond" (isma) is that which one holds onto, such as a contract or tie. It means: Keep away from them; let there be no marital bond or connection between you and them. Ibn Abbas said: Whoever had a disbelieving wife in Mecca should not count her among his wives, because the separation of the two abodes (the House of Islam and the House of Disbelief) severs the bond.

{And if anything has escaped you} If any of your wives have slipped away from you to the disbelievers. If you ask: Is there a benefit in using the word "anything" (shay') here? I say: Yes, the benefit is that not a single thing of this kind—no matter how small or insignificant—should be left uncompensated, as a way of emphasizing and strengthening this ruling.

{Then you have taken your turn} Derived from "the turn" (al-'uqbah), which is the rotation. It likens the ruling—that Muslims pay the dowries of the women who left, and the disbelievers pay the dowries of the women who came—to a matter in which they take turns, just as one takes turns in riding. It means: Your turn has come to pay the dowry; so give the one whose wife escaped to the disbelievers the equivalent of her dowry from the dowry of the immigrant woman, and do not give it to her disbelieving husband.