his liability. For example, if one dinar is worth ten dirhams and he says, “I will take eleven from you,” this is not permissible, because the one who takes eleven in exchange for the dinar has gained one dirham; thus, he has profited from something that has not come under his liability. The dinars remain the liability of the person who owes them and have not yet come into his possession. The Prophet, peace and blessings be upon him, forbade profiting from that for which one has not assumed liability.
We previously stated that an implication by contrast does not carry general applicability, for it is fulfilled by even a single contrary instance. Thus, if he takes it for less than its price on that day—meaning that the dinar is worth ten, but the creditor takes nine—the implication of the hadith, “There is no harm in taking it at its price on that day,” would be that this case is impermissible. Yet it is, in fact, permissible, because he has not profited from something that has not come under his liability. Rather, he has given up part of his due and released the debtor from part of what he owes. There is no harm in releasing someone from part of one’s due.
It thus becomes clear that this implication does not have general applicability. This is an issue that the student of knowledge should understand: an implication by contrast is not general, but is fulfilled by one contrary instance. In the example, that one contrary instance is where he takes more: the dinar is worth ten, but he takes eleven. This is impermissible because it constitutes profiting from that for which one has not assumed liability.
We have understood the rationale behind the Prophet’s statement, peace and blessings be upon him: “There is no harm in taking it at its price on that day.” What, then, is the rationale behind his statement: “so long as you do not part while anything remains outstanding between you”?
The answer is also clear: he will be taking dirhams in exchange for dinars, and when dinars are exchanged for dirhams, possession must be taken during the contracting session. Therefore, if possession is not taken, the contract is invalid—just as it is invalid if one sells dinars for dirhams without taking possession. It thus becomes clear that the hadith of Abdullah ibn Umar