Translation:

10. O ye who believe! when there come to you believing women refugees examine (and test) them: Allah knows best as to their Faith: if ye ascertain that they are Believers then send them not back to the Unbelievers. They are not lawful (wives) for the Unbelievers nor are the (Unbelievers) lawful (husbands) for them. But pay the Unbelievers what they have spent (on their dower). And there will be no blame on you if ye marry them on payment of their dower to them. But hold not to the guardianship of unbelieving women: ask for what ye have spent on their dowers and let the (Unbelievers) ask for what they have spent (on the dowers of women who come over to you). Such is the command of Allah: He judges (with justice) between you: and Allah is Full of Knowledge and Wisdom.

Notes (Tafseer)

5422. Under the treaty of Hudaibiya [see Introduction to S. xlviii, paragraph 4, condition (3)], women under guardianship (including married women), who fled from the Quraish in Makkah to the Prophet's protection at Madinah were to be sent back. But before this Ayat was issued, the Quraish had already broken the treaty, and some instruction was necessary as to what the Madinah Muslims should do in those circumstances. Muslim women married to Pagan husbands in Makkah were oppressed for their Faith, and some of them came to Madinah as refugees. After this, they were not to be returned to the custody of their Pagan husbands at Makkah, as the marriage of believing women with non-Muslims was held to be dissolved if the husbands did not accept Islam. But in order to give no suspicion to the Pagans that they were badly treated as they lost the dower they had given on marriage, that dower was to be repaid to the husbands. Thus helpless women refugees were to be protected at the cost of the Muslims.

5423. The condition was that they should be Muslim women. How were the Muslims to know? A non-Muslim woman, in order to escape from her lawful guardians in Makkah, might pretend that she was a Muslim. The true state of her mind and heart would be known to Allah alone. But if the Muslims, on an examination of the woman, found that she professed Islam, she was to have protection. The examination would be directed (among other things) to the points mentioned in verse 12 below.

5424. As the marriage was held to be dissolved (see n. 5422 above), there was no bar to the remarriage of the refugee Muslim woman with a Muslim man on the payment of the usual dower to her.

5425. Unbelieving women in a Muslim society would only be a clog and a handicap. There would be neither happiness for them, nor could they conduce in any way to a healthy life of the society in which they lived as aliens. They were to be sent away, as their marriage was held to be dissolved; and the dowers paid to them were to be demanded from the guardians to whom they were sent back, just as in the contrary case the dowers of believing women were to be paid back to their Pagan ex-husbands (n. 5422 above).