Silsilah Sahihah

It is narrated from Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) sent ‘Itab bin Usayd towards Makkah (as a governor) and said: “Do you know where I am sending you? To the people of Allah, who are the people of Makkah. You must prohibit them from these four things: (1) That there be both a sale and a loan in one transaction, (2) two conditions in one sale, (3) profit from something for which a person does not bear the loss, and (4) selling something which is not with you.”

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Whoever makes two transactions in one sale, he will either take the lesser price or he will take usury."