this is permissible, because the rights of the slave woman have not yet come into existence, so she has not wronged anyone. Likewise, if she stipulates that he not marry another woman, this is permissible.
Some scholars said that it is not permissible, because it restricts the husband with regard to what Allah has made lawful for him, and thus contradicts the Quran: “Marry such women as are lawful to you: two, three, or four.” [al-Nisa’ 4:3] The response is that she has a legitimate interest in his not marrying another woman, and she has not wronged anyone. Moreover, it is the husband himself who has waived his right. If he has the right to marry more than one woman and waives it, then what prevents this condition from being valid? Therefore, the sound view in this matter is that held by Imam Ahmad, may Allah have mercy on him: namely, that this is a valid condition.
If it is asked: What is the difference between this case and the first case?
The answer is that the difference between them is evident: in the first case, the man is already married, whereas here he is not married. Thus, in this latter case, there is no wrongdoing against anyone. Hence it is said: preventing something is easier than removing it. This is a well-known principle of fiqh, and maintaining an existing state is weightier than initiating it. Furthermore, fulfilling this condition is also more in keeping with honorable conduct and good character. For it is not noble conduct to marry a woman on the condition that you will not marry another woman over her, then, after deflowering her and leaving her less sought after among people, go and marry another woman over her!
Issue: If they said to the husband, “We stipulate that if you marry another woman, she is divorced,” and he replied, “You may stipulate that I do not marry; and if I do marry, she is divorced,” then the condition that he not marry is valid. But if he does marry, is she divorced? No, because this is making divorce conditional upon something he does not possess. Divorce can only take place after marriage, and this man has not married such that he could divorce. Thus, if a woman heard that her husband intended to marry another woman