Anas said that a man of Kilab asked the Prophet about hiring a stallion to cover a female and he forbade him; but when he said, "Messenger of God, we lend a stallion to cover a female and are given a present," he gave him licence to accept a present.
Hakim b. Hizam said God's Messenger forbade him to sell anything which was not in his possession.
Tirmidhi transmitted it.
In a version by Abu Dawud and Nasa’i, he had said, “Messenger of God, a man comes to me and wants me to sell him something, but I do not have it and so I buy it for him from the market.” He replied, “Do not sell what you do not possess.”
‘Amr b. Shu'aib, on his father’s authority, said his grandfather told that God’s Messenger forbade the type of transaction in which earnest money was paid (An arrangement by which the earnest-money was treated as part of the price if the deal was completed but was retained if it was not completed).