Did the Companions, during the time of the Prophet, peace and blessings be upon him, stipulate to their husbands that they not marry another woman? And is that considered a prohibition of what Allah has made lawful? What is the ruling on a husband promising his wife not to marry another woman if it is after the marriage? Is he obligated to fulfill it even if it was made under duress? And is the husband sinful if he does not fulfill his promise?

If a woman stipulates to her husband that he must not marry another woman, this is a valid condition that must be fulfilled. If he then marries another woman, she has the right to annul the marriage, based on the Prophet's (peace and blessings be upon him) saying: "The conditions most worthy of fulfillment are those by which you make intimacy lawful," and his saying: "Muslims are bound by their conditions, except for a condition that forbids what is lawful or permits what is unlawful." This condition does not forbid what is lawful; rather, it restricts the husband's authority. However, if the condition is made after the marriage contract, it is considered a promise and does not grant the wife the right to annul the marriage, but the husband must fulfill it based on the general evidence that commands fulfillment of covenants and promises.