It is narrated from Hazrat Abu Hurairah (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: He forbade two types of buying and selling and two types of clothing. As for clothing, it is that a person sits wrapped in a single garment with nothing covering his private parts, and that a person wraps himself in a single garment as a cloak, lifting both its ends onto his shoulder. And he forbade the sale by "mulamasa" and the sale by throwing a stone. Benefit: The meaning of "bay‘ mulamasa" is that the buyer says, "Whatever thing I touch with my hand will be mine for such and such amount."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10370