Praise be to Allah.
Abu Ja’far Muhammad ibn Jareer al-Tabari gave a definition of muhsanah in Jaami’ al-Bayaan ‘an Ta’weel Aayi’l-Qur’aan (8/165):
“Muhsanah means the woman who is chaste and pure … one who is chaste and protects her private parts from committing immoral acts, as in the aayah (interpretation of the meaning): ‘And Maryam, the daughter of ‘Imraan, who guarded her chastity…’ [al-Tahreem 66:12], meaning that she kept herself above suspicious actions and protected herself from immoral conduct.”
Then he discussed the interpretation of the aayah (interpretation of the meaning): ‘… (lawful to you in marriage) are chaste women from the believers and chaste women from those who were given the Scripture (Jews and Christians) before your time…’ [al-Maa’idah 5:5]
He said that some others said that what was meant by this aayah (‘… (lawful to you in marriage) are chaste women from the believers and chaste women from those who were given the Scripture (Jews and Christians) before your time…’) is chaste women from both groups, whether they were slaves or free. Those who were of this opinion considered it permissible to marry slave women who were Jews or Christians who practised their religions, because of this aayah, but they considered it haraam to marry promiscuous women, whether they were Muslims or from the People of the Book. Then he mentioned reports to support this opinion.
He also said: ‘There was some dispute among the scholars about the interpretation of the phrase and chaste women from those who were given the Scripture (Jews and Christians) before your time…- was this general or specific in application? Some said that it is general and applies to all chaste women, because muhsanaat means chaste women, and a Muslim is allowed to marry any woman of the People of the Book, free or slave, from a country whose people are engaged in hostilities with Islam or from a community which is living under Islamic rule. They use as evidence for this the apparent meaning of the phrase and chaste women from those who were given the Scripture (Jews and Christians) before your time… - taking muhsanaat to mean any chaste woman, whoever she may be. This is the opinion of those who take muhsanaat to mean “chaste women” in this context.
Others say that it refers only to the women of Jewish and Christian communities who are living under Islamic rule. As regards those living in regions that are hostile to Islam, Muslims are not permitted to marry such women.
He mentions an important condition for marrying a woman of the People of the Book, which every Muslim who wants to marry such a woman in a non-Muslim country should pay attention to. This condition is that he should be in a position where he is not afraid that his child will be forced into kufr.
One of the obvious implications of this in our time is that a Muslim should not put himself in a position where he will be forced to raise his child as a kaafir in a non-Muslim country, where a child may be forced to study something about Christianity, for example, or he may be taken to church on Sundays, or the law may be on the side of the non-Muslim woman, allowing her to take her child wherever she wants and raise him in her family’s religion, etc. We ask Allaah to keep us safe from all that and we seek refuge with Him from being forsaken.
Shaykh al-Sa’di said in his Tafseer (commentary on the Qur’aan), 1/458:
“‘… (lawful to you in marriage) are chaste women – i.e., free and chaste - from the believers and chaste women –free and chaste - from those who were given the Scripture (Jews and Christians) before your time…’ i.e., from among the Jews and Christians. This is adding specific details to the aayah (interpretation of the meaning): ‘And do not marry al-mushrikaat (idolatresses, etc.) till they believe (worship Allaah alone)…’ [al-Baqarah 2:221].”
As for promiscuous women, those who do not keep themselves chaste and free from immoral sexual conduct, it is not permitted to marry them, whether they are Muslims or from among the People of the Book (Jews and Christians), unless they repent, because Allaah says (interpretation of the meaning): “Let no man guilty of fornication or adultery marry any but a woman similarly guilty, or an unbeliever: nor let any but such a man or an unbeliever marry such a woman: to the Believers such a thing is forbidden.” [al-Noor 24:3]
And Allaah knows best.