question #1 Sahih al-Bukhari 2170, Book 34, Hadith 121 : What conditions must be met to avoid Riba when exchanging similar commodities like wheat or barley?

The Prophet (ﷺ) said, “The selling of wheat for wheat is Riba (usury) except if it is handed from hand to
hand and equal in amount. Similarly the selling of barley for barley, is Riba except if it is from hand to
hand and equal in amount, and dates for dates is usury except if it is from hand to hand and equal in
amount. (See Riba-Fadl in the glossary).