Imam Malik's Muwatta, Chapter: Business Transactions

Yahya related to me from Malik from Abd al-Hamid ibn Suhayl ibn Abd ar-Rahman ibn Awf from Said ibn al-Musayyab from Abu Said al-Khudri and from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, appointed a man as an agent in Khaybar, and he brought him some excellent dates. The Messenger of Allah, may Allah bless him and grant him peace, said to him, "Are all the dates of Khaybar like this?" He said,"No. By Allah, Messenger of Allah! We take a sa of this kind for two sa or two sa for three." The Messenger of Allah, may Allah bless him and grant him peace, said, "Do not do that. Sell the assorted ones for dirhams and then buy the good ones with the dirhams."