question #1 Sahih al-Bukhari 2312, Book 40, Hadith 12 : What is the Islamic ruling on exchanging goods of different qualities in unequal quantities?

Once Bilal brought Barni (i.e. a kind of dates) to the Prophet (ﷺ) and the Prophet (ﷺ) asked him, “From where
have you brought these?” Bilal replied, “I had some inferior type of dates and exchanged two Sas of it
for one Sa of Barni dates in order to give it to the Prophet; to eat.” Thereupon the Prophet (ﷺ) said,
“Beware! Beware! This is definitely Riba (usury)! This is definitely Riba (Usury)! Don’t do so, but if
you want to buy (a superior kind of dates) sell the inferior dates for money and then buy the superior
kind of dates with that money.”