Sunan Ibn Majah 2354

Azhar bin Marwan narrated to us: Abd Al-Ala narrated to us: Said narrated to us, from Qatadah, from Anas bin Malik, that a man in the time of the Messenger of Allah (peace and blessings be upon him) had weakness in his judgment and would engage in sales. His family came to the Prophet and said: Messenger of Allah, place a restriction on him. The Prophet called him and forbade him from that, but he said: Messenger of Allah, I cannot bear to abstain from buying and selling. He said: When you make a transaction, say: Here it is, and there is no deception.