He—may Allah Most High have mercy on him—was asked:

A man gave his wife a gift of one thousand dirhams and had a deed drawn up acknowledging his liability for that sum, but he did not deliver any of it to her. She died, and her heirs demanded the amount from him. May he revoke the gift?

He replied:

Praise be to Allah. If he previously owed her nothing—neither this amount nor anything for which this amount could serve as compensation, such as having taken some of her trousseau and agreed with her to pay this amount in settlement of its value, or something similar—then her heirs are not, in reality, entitled to any of this debt. If there is an acknowledgment of debt, he may require them to swear that they do not know that the reality behind this acknowledgment differs from its outward purport. If evidence establishes against both the person making the acknowledgment and its beneficiary that the acknowledgment was a sham, then it has no basis in reality.

If the property of hers to which his acknowledgment related was worth less than this amount, but he agreed to a settlement with her for more than its value, scholars differ over whether this excess is binding. Some scholars among the followers of al-Shāfi'ī and Ahmad hold it invalid, whereas Abū Hanīfah holds it valid. The latter also follows by analogy from the position of Ahmad and others, and it is the correct view. And Allah knows best.