Sahih al-Bukhari 2175

that Malik bin Aus said, "I was in need of change for one-hundred Dinars. Talha bin 'Ubaidullah called me and we discussed the matter, and he agreed to change (my Dinars). He took the gold pieces in his hands and fidgeted with them, and then said, "Wait till my storekeeper comes from the forest." `Umar was listening to that and said, "By Allah! You should not separate from Talha till you get the money from him, for Allah's Messenger (ﷺ) said, 'The selling of gold for gold is Riba (usury) except if the exchange is from hand to hand and equal in amount, and similarly, the selling of wheat for wheat is Riba (usury) unless it is from hand to hand and equal in amount, and the selling of barley for barley is usury unless it is from hand to hand and equal in amount, and dates for dates, is usury unless it is from hand to hand and equal in amount

(Concerning exchange) that he heard Allah's Messenger (ﷺ) saying, "Do not sell gold for gold unless equal in weight, and do not sell silver unless equal in weight

The Prophet (ﷺ) forbade Muzabana; and Muzabana is the selling of fresh fruit (without measuring it) for something by measure on the basis that if that thing turns to be more than the fruit, the increase would be for the seller of the fruit, and if it turns to be less, that would be of his lot. Narrated Ibn `Umar from Zaid bin Thabit that the Prophet (ﷺ) allowed the selling of the fruits on the trees after estimation (when they are ripe)