What constitutes a sufficiently known and specified term for a deferred payment?
Chapter on Guaranteed Salaf (Advance Payment) for a Specified Term
Al-Mughni
Book of Sales
Primary text
The term must be specified by a precise time that does not vary. It is not valid to specify the term by imprecise events such as the harvest or threshing. This position is held by Ibn Abbas, Abu Hanifa, Al-Shafi'i, and Ibn al-Mundhir. The evidence against imprecise terms is based on the report from Ibn Abbas that one should not contract sales until the harvest or threshing, but only until a known month. Furthermore, terms that vary and can approach or recede, like the arrival of Zayd, are invalid as a deferred period because they introduce ambiguity, similar to uncertain events.
Supporting text
There is a differing report from Ahmad, supported by Malik and Abu Thur, indicating hope that specifying the term by events like 'the time of receiving the stipend (Al-'Ata')' or 'the arrival of the raiding force (Al-Ghuzat)' might be permissible, provided the time is conventionally known to be fixed, even if the exact date varies slightly. Ibn Umar reportedly engaged in transactions linked to the stipend, a view also held by Ibn Abi Layla. This allowance rests on the argument that such an event relates to a time conventionally known and does not vary significantly, thus resembling specification until the turn of the year.