He—may Allah have mercy on him—also said, after an earlier discussion:

The principle underlying this issue is that a prohibition indicates that the harm in what is prohibited outweighs its benefit. It is not prescribed for someone to commit himself to harm when he is enjoined to avert it. The foundation of this is that whenever Allah prohibits something in certain circumstances but permits it in others, its prohibited form cannot be valid and legally effective like its permissible form, producing the same legal consequences and achieving the same intended purpose.

This is what is meant by the statement, “Prohibition entails invalidity.” This is the position of the Companions, those who followed them in righteousness, the leading scholars of the Muslims, and their majority. Many speculative theologians among the Mu‘tazilīs and Ash‘arīs disagree, supposing that some prohibited acts are not invalid, such as an unlawful divorce or prayer in a usurped house, and similar cases.

Their argument is: “If prohibition entailed invalidity, these cases would constitute counterexamples to that causal principle. This shows that invalidity arises from some cause other than prohibition as such.” These men were not among the leading jurists versed in the detailed evidence of Islamic law.

They were therefore asked, “How can one know that an act of worship or a contract is invalid?”

They replied, “By the Lawgiver saying: ‘This is valid, and this is invalid.’” Yet these men were unfamiliar with the evidence of