Sahih al-Bukhari Book 68, Hadith 34
Whenever Ibn `Umar was asked about marrying a Christian lady or a Jewess, he would say: "Allah
has made it unlawful for the believers to marry ladies who ascribe partners in worship to Allah, and I
do not know of a greater thing, as regards to ascribing partners in worship, etc. to Allah, than that a
lady should say that Jesus is her Lord although he is just one of Allah's slaves."
Aisha intended to buy Barira, but her masters stipulated that her wala wound be for them. Aisha mentioned that to the Prophet (ﷺ) who said (to `Aisha), "Buy and manumit her, for the wala is for the one who manumits." Once some meat was brought to the Prophet (ﷺ) and was said, "This meat was given in charity to Barira. " The Prophet (ﷺ) said, "It is an object of charity for Barira and a gift for us."
Narrated Adam: Shu`ba related the same Hadith and added: Barira was given the option regarding her husband.
The pagans were of two kinds as regards their relationship to the Prophet and the Believers. Some of them were those with whom the Prophet was at war and used to fight against, and they used to fight him; the others were those with whom the Prophet (ﷺ) made a treaty, and neither did the Prophet (ﷺ) fight them, nor did they fight him. If a lady from the first group of pagans emigrated towards the Muslims, her hand would not be asked in marriage unless she got the menses and then became clean. When she became clean, it would be lawful for her to get married, and if her husband emigrated too before she got married, then she would be returned to him. If any slave or female slave emigrated from them to the Muslims, then they would be considered free persons (not slaves) and they would have the same rights as given to other emigrants. The narrator then mentioned about the pagans involved with the Muslims in a treaty, the same as occurs in Mujahid's narration. If a male slave or a female slave emigrated from such pagans as had made a treaty with the Muslims, they would not be returned, but their prices would be paid (to the pagans).