Tirmidhi

Explanation:
1:
Because there is deception in it,
the object of sale (the commodity) is unknown.

The cloth is mentioned merely as an example; otherwise, if anything is sold or bought in this manner, it will be termed mulamasah and munabadhah. It is also not necessary that the items on both sides be of the same kind, as has been mentioned in the commentary; rather, even if the transaction is with cash, the same ruling applies. The point is that any transaction in which there is ambiguity or the possibility of deception is prohibited, because such transactions later become a cause of disputes and quarrels. Furthermore, their basis is selfishness and deceit, and both of these are contrary to humanity and to Islam.

(1) Bay‘ mulamasah is forbidden because it is nothing but pure deception, whereas, both legally and ethically, deceiving someone is absolutely impermissible.

(2) It is also understood from the hadith that bay‘ munabadhah is forbidden. The reason for this is the same as mentioned above.

(3) From this blessed hadith, there is also a subtle indication that in the days of ignorance (Jahiliyyah), the unlawful transactions that were prevalent among people, and which led to mutual conflict and severance of relations, the Lawgiver (sallallahu alayhi wa sallam) was extremely eager to distance his ummah from all such dealings that could become a cause of discord in their mutual relations and could give rise to enmity and hatred among them. Bay‘ mulamasah and munabadhah, and other prohibited sales, are also of this category. However, despite all this, the greed and desire for wealth and money have blinded the majority of people; accumulating wealth has been considered the very purpose of life, and in this pursuit, no distinction is made between what is lawful (halal) and unlawful (haram).

The interpretations of mulamasah and munabadhah may vary, but one thing is common between them: apart from touching and throwing, there remains no further scope for certainty or satisfaction. This very ambiguity is, in fact, the reason for the prohibition of such types of sales, while at the same time, in all these cases, an element of deception is also present.