Sunan At-Tirmidhi

Narrated Abu Hurairah: ""The Messenger of Allah (ﷺ) prohibited sales of Al-Munabadhah and Al-Mulamasah."" He said: There are narrations on this topic from Abu Sa'eed and Ibn 'Umar. [Abu 'Eisa said:] The Hadith is Abu Hurairah is a Hasan Sahih Hadith. And the meaning of (Munabadhah) in this Hadith is when it is said: ""When I throw something to you then the sale between you and I is concluded."" And Al-Mulamasah is that he says: ""When you touch something then the sale is concluded."" Even if he did not see it at all, like if it was inside of a bag or something else. There are merely sales practices of the people of Jahiliyyah so they were prohibited