Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) says that ishtimal al-samma' is that he puts both ends of a single garment on his left shoulder while the right shoulder is left uncovered; al-munabadhah is that he says: "When I have thrown this garment, the sale is binding"; and al-mulamasah is that he touches the garment with his hand without spreading it out or turning it over, and once he has touched it, the sale becomes binding.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10871