Sahih Al Bukhari – Book of Representation, Authorization, Business By Proxy

Volumn 003, Book 038, Hadith Number 499.
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Narated
By Abu Said Al-Khudri and Abu Huraira : Allah’s Apostle employed
someone as a governor at Khaibar. When the man came to Medina, he
brought with him dates called Janib. The Prophet asked him, “Are all the
dates of Khaibar of this kind?” The man replied, “(No), we exchange two
Sa’s of bad dates for one Sa of this kind of dates (i.e. Janib), or
exchange three Sa’s for two.” On that, the Prophet said, “Don’t do so,
as it is a kind of usury (Riba) but sell the dates of inferior quality
for money, and then buy Janib with the money”. The Prophet said the same
thing about dates sold by weight. (See Hadith No. 506).
Bu