Musannaf Ibn Abi Shaybah

Ibrahim says that a forward sale (bay' salam) should not be conducted of measured items in exchange for measured items, nor should a forward sale be conducted of weighed items in exchange for weighed items.

Hazrat Tawus says that Salam sale should not be done of food in exchange for food, nor should Salam sale be done of meat in exchange for meat. However, he did not see any harm in conducting a Salam sale of food in exchange for a live goat.

Hazrat Sha’bi (may Allah have mercy on him) says: Do not sell measured items for measured items in Salam transactions.

Hasan and Hazrat Qatadah disliked giving food in exchange for food as payment.

Hasan says that there is no harm in making salam (advance payment contract) of measured things with measured things and of weighed things with weighed things; indeed, this is receiving food in exchange for food.