Abu Sa'id al-Khudri · Commercial Transactions (Kitab Al-Buyu)

The Prophet (ﷺ) forbade the type of sale which involves risk (or uncertainty) and a transaction determined by throwing stones.

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.

"Wearing the samma' means that a man puts his garment over his left shoulder and keeps his right side uncovered. Munabadhah means that a man says (to another): If I throw this garment to you, the sale will be certain. Mulamasah means that a man touches it (another's garment) with his hand and neither he unfolds it nor turns it over. When he touched it, the sale becomes binding.