What is the meaning of the condition that the Muslim be in the care of (under the protection of) Allah?

Salam is one of the permissible types of sale. It is the sale of a described item held in trust, with payment given immediately. It is stipulated that the item being sold (the muslam fihi) must be deferred to a known term according to the majority of scholars, based on the Prophet's (peace be upon him) saying: "Whoever pays in advance for something, let him pay in advance for a known measure or a known weight until a known term." The Shafi'is, however, permit immediate salam.