al-Hasan bin 'Ali al-Halwani الحسن بن علي الخلال الحلواني · Commercial Transactions (Kitab Al-Buyu)

The Messenger of Allah (ﷺ) as saying: Gold for gold is interest unless both hand over on the spot ; wheat for wheat is interest unless both hand over on the spot ; dates for dates is interest unless both hand over on the spot ; barley for barley is interest unless both hand over on the spot.

The Messenger of Allah (ﷺ) forbade the sale of fruits until they are ripened (tushqihah). He was asked: What do you mean by their ripening (ishqah)? He replied: They become red or yellow, and they are eaten.

The Prophet (ﷺ) forbade two types of business transactions and two ways of dressing. The two types of business transactions are mulamasah and munabadhah. As regards the two ways of dressing, they are the wrapping of the samma', and that when a man wraps himself up in a single garment while sitting in such a way that he does not cover his private parts or there is no garment on his private parts.