Our teacher, Muhammad ibn Al-Hasan (may Allah سبحانه وتعالى be pleased with him), said: Whenever a financial agreement (qabalah) is established between two men before a third party for a specified term, and they write an agreement between them to obligate themselves to abide by it, the intermediary must act according to the agreement and not exceed it. It is not permissible for him to delay returning that written agreement to its rightful owner at the time it is due. I also heard him (our teacher Muhammad ibn Al-Hasan), may Allah سبحانه وتعالى be pleased with him say: I heard our elders (may Allah سبحانه وتعالى be pleased with them) say that agreements are not treated as binding judgments (ahkam). If agreements were treated as judgments, they would be invalidated. Muslims are bound by their conditions as long as they conform to the Book of Allah سبحانه وتعالى, the Mighty and Exalted. If the debtor brings part of the payment at the due time or before it, but does not pay the full amount, the intermediary must verify the amount received from the debtor by documenting it in the presence of witnesses - if the debtor is solvent. If the debtor is not solvent, then additional security should be required. If the intermediary instructs the return of the payment to the person from whom it was received, this would be preferable and more secure. If the agreement specifies terms different from this, the intermediary should enforce them, if Allah سبحانه وتعالى wills.
Commentary #1