(O ye who believe! When believing women) who truly believe in Allah (come unto you as fugitives) from Mecca to Medina or al-Hudaybiyyah, (examine them) ask them and let them swear as to their intentions from their coming. (Allah is best aware of their faith) Allah is best aware of their hearts' firmness in faith. (Then, if ye know them for true believers) through examination, (send them not back unto the disbelievers) do not send them back to their disbelieving husbands. (They are not) i.e. the believing women, (lawful for the disbelievers) for their disbelieving husbands, (nor are the disbelievers lawful for them) for the believing women. Allah says: a believing woman is not lawful for a disbelieving man nor is a disbelieving woman lawful for a believing man. (And give the disbelievers that which they have spent (upon them)) give their husbands that which they have spent on them as dower. This was revealed about Subay'ah Bint al-Harth al-Aslamiyyah who came to the Prophet (pbuh) in the year of al-Hudaybiyyah, to declare her Islam but her husband Musafir came after her to take her back. The Prophet, Allah bless him and give peace, gave him back the dowry which her husband had given her. In that particular year, and before the revelation of this verse, the people of Mecca had signed a treaty with the Prophet (pbuh) which stipulated that whoever from the people of Mecca embraces Islam can join the Muslims, and whoever of the Muslims embraces the religion of the Meccan pagans is returned to the Muslims; and any woman from the people of Mecca who embraces Islam, the Muslims should pay back the dowry given to her to her husband, and any Muslim woman who joins the religion of the Meccan pagans, the people of Mecca should pay back her dowry to her husband. This is why the Prophet (pbuh) paid back to Musafir the dowry which he had given to Subay'ah. (And it is no sin for you) O believers (to marry such women) those who were disbelievers and then embraced Islam (when ye have given them their dues) when you have given them their dowry. Allah says here: any woman who embraces Islam while her husband remains a disbeliever, the sacred bond that ties her to her husband becomes broken and, therefore, she does not have to observe a waiting period and can marry after making sure she is not pregnant.
