It is narrated from Hazrat Abu Sa'id Khudri (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) forbade the sale of Mulamasa, which is when a person touches a cloth without properly examining it (and he has to buy it). He also forbade the sale of Munabadha, which is when a person looks at clothes or something similar and, before properly turning it over and examining it, throws it towards the buyer.