are legal analogy and reasoning based on the other foundational principles of Islamic law. Any contract that is permissible in some circumstances and forbidden in others—such as a sale or marriage—does not, when concluded in a forbidden manner, have the binding legal effect of a lawful contract permitted by Allah and His Messenger. Thus, Muslims agree that marriages forbidden by Allah, such as marriages within the prohibited degrees or marriage to a woman during her waiting period, are void and nonbinding. The same applies to the sale of things Allah has forbidden, such as wine, swine, and carrion.
This differs from acts that are forbidden by their very nature, such as zihār (declaring one’s wife forbidden by likening her to a prohibited female relative), accusations of unchastity, lying, false testimony, and the like. Whoever commits such an act deserves punishment in accordance with the rulings Allah has prescribed. These acts are not lawful in some circumstances and unlawful in others, such that they might sometimes be valid and sometimes invalid.
Other transactions are forbidden for one party but permissible for the other. Examples include ransoming a captive; purchasing someone whose emancipation is denied; bribing an oppressor to ward off his oppression or secure a right he is obliged to grant; buying an animal whose milk has deliberately been allowed to accumulate in its udder, or an item whose defect has been concealed; giving money to those whose hearts are to be won over so that they fulfil an obligation or refrain from something forbidden; and an incoming trader selling to someone who intercepts him. In such cases and others like them, the wronged party may permissibly enter into the transaction and may either rescind the contract or uphold it. By contrast, the wrongdoer’s act is not binding.
Divorce is among the things Allah has permitted in some circumstances and forbidden in others. When it is carried out in a manner forbidden by Allah and His Messenger, it does not have the binding legal effect of what Allah and His Messenger have made lawful. As is reported in the two Sahīh collections from ‘Ā’ishah (may Allah be pleased with her), the Prophet (may Allah bless him and grant him peace) said: