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

“Two people released one another from liability and had witnesses attest to their acknowledgment that neither had any right to demand payment from, or bring a claim against, the other concerning a dinar or a dirham, or anything less or more. One of them, however, owed the other a specified sum in dirhams recorded in a legally valid document. The creditor excepted this debt when granting the release: he did not discharge the debtor from the obligation recorded in that document, nor did he mention it in the mutual release.

“When the creditor demanded payment on the strength of the document, the other party said, ‘Did we not release one another from liability?’ He replied, ‘I released you from everything except the debt recorded in this document.’ May his legal claim based on that document be heard?”

He replied:

“If he claims that he did not release the debtor from that obligation, that the debtor knows he did not release him from it, and requests the debtor’s oath that the creditor had not released him from it, he is entitled to do so.”