Consider, then, what is stipulated, whether it is an act or a legal ruling. If Allah has permitted it, it may validly be stipulated, and fulfilling it becomes obligatory. If Allah Most High has not permitted it, it may not be stipulated.

Thus, if a man stipulates that he will not take his wife travelling, this stipulation is in Allah’s Book, because Allah’s Book permits him not to take her travelling. By stipulating that he will not travel with her, he has stipulated something permissible in Allah’s Book.

The substance of the hadith, then, is that if the matter stipulated is not among permissible acts, [the stipulation is invalid]. Alternatively, “not in Allah’s Book” may be explained as meaning that its negation is not in Allah’s Book, just as he said:

“There will be people who tell you things that neither you nor your forefathers have known.”

That is, things contrary to what you know. Otherwise, there are many things one does not know.

We further say: the Prophet (peace and blessings be upon him) did not mean that contracts and conditions which the Lawgiver has not permitted are invalid in the sense that they entail no binding consequences—neither obligations nor prohibitions. This would contradict the Quran and Sunnah. Rather, prohibited contracts and conditions may entail legal consequences.

Allah prohibited the declaration of zihār (declaring one’s wife as forbidden to oneself as one’s mother) in His Book itself, calling it a reprehensible utterance and a falsehood. Yet He made expiation obligatory for anyone who goes back on that declaration. For one who does not go back on it, He gave effect to the intended prohibition: refraining from intercourse and from entering into a marriage contract.

The same applies to vows. The Prophet (peace and blessings be upon him) forbade making vows, as is authentically reported from him in the hadiths of Abū Hurayrah and Ibn ‘Umar, and said:

“It brings no good.”

Yet he required a vow to be fulfilled when it involved obedience to Allah, as stated in