Malik said, from Nafi from Abdullah ibn Umar that the Messengerof Allah, may Allah bless him and grant him peace, forbade najsh.Malik said, "Najsh is to offer a man more than the worth of hisgoods when you do not mean to buy them and someone else follows you inbidding."
USC-MSA web (English) reference: Book 31, Hadith 98
Arabic reference: Book 31, Hadith 1384