Musannaf Ibn Abi Shaybah

Muhammad bin Zaid (may Allah have mercy on him) says that I asked Hazrat Ibn Umar (may Allah be pleased with them) that sometimes a person enters into a salam sale with someone for one thousand dirhams, and says: If you give me wheat, the deal will be for such and such amount, and if you give barley, then for such and such amount. He (may Allah be pleased with him) replied: For each type (kind), state a separate price; if he gives it to me at that price, then fine, otherwise take back your principal amount from him.

It is narrated from Hazrat Saeed bin Jubair (may Allah have mercy on him) that if a person, while conducting a Salam sale, says: "Whatever wheat you have is for such-and-such amount, and whatever grains you have is for such-and-such amount," then doing so is disliked.

Hazrat Aamir was asked about the Salam sale of wheat and barley, whether one can deliver whichever is easily available? He, may Allah have mercy on him, replied: The sale does not have the capacity for this. (It is not correct.)

Hazrat Ata (may Allah have mercy on him) was asked if a person enters into a Salam sale for a specified item for a specified period, and if he is unable to deliver that item in that quantity, can he deliver another specified item in that quantity instead? He (may Allah have mercy on him) replied that this is not permissible.

It was asked from Hasan (may Allah have mercy on him) that if a person makes a salam (forward sale) saying: "If it is wheat, then for such an amount, and if it is barley, then for such an amount," what is the ruling? He (may Allah have mercy on him) disliked this.