1. The amount of the goods sold on salam must be specified by the legally recognized measure or weight when they are sold by measure or weight; by linear measure when they are customarily measured by length; or by count when they are sold by number—provided that the items counted do not differ markedly from one another in size, quality, or the like.
2. Delivery must be set for a deferred date, and that term must be known. A salam contract is therefore invalid if delivery is to be immediate or if the deadline is vague or unknown.
3. The price must be handed over in the very session in which the contract is concluded. This is taken from his words, “let him pay in advance,” for salaf (salam) refers to a sale in which the price is advanced and the commodity deferred.
4. The obligation is contracted as a liability, not with respect to specific existing items. This is what makes the agreement permissible even though fulfillment will come from fruit or crops that do not yet exist at the time of contracting.

From this it is evident that salam does not fall under the prohibition expressed in the words, “Do not sell what you do not possess,” and that contracting on it conforms to sound analogy. These are the most important conditions that are to be observed. Some jurists nonetheless tightened the matter with further restrictions for which no clear proof exists.

Chapter: Stipulations in Sale

The default ruling on stipulations is that they are valid and binding upon the party on whom they are set, in light of the Prophet’s ﷺ saying: “Muslims are bound by their stipulations, unless a stipulation permits what Allah has forbidden or forbids what He has permitted.”

First Hadith

ʿĀʾishah (may Allah be pleased with her) said: Barīrah came to me and said, “I have entered into a mukātabah with my owners for nine awāq, one uqiyyah each year. Help me.” I replied, “If your owners agree that I pay them the whole sum and your walāʾ (right of clientage) is mine, I will do so.” Barīrah went to her owners and told them, but they refused. She then returned—while the Messenger of Allah ﷺ was sitting there—and said, “I offered that to them, but they insist that the walāʾ must remain theirs.” ʿĀʾishah relayed this to the Prophet ﷺ, and he said, “Buy her and stipulate that the walāʾ is theirs, for walāʾ belongs only to the one who sets the slave free.” So ʿĀʾishah did so. Then the Messenger of Allah ﷺ stood before the people, praised Allah, and extolled Him,