A man offered his goods for sale and swore by Allah that he had been given a price for them which in fact he had not been given, so this verse was revealed, "Those who sell the covenant of Allah and their oaths for a small price" [Al Imran 3:77].Ibn Abi Awfa said, "The one who raises a bid without intending to buy devours usury and is a traitor."
أقام رجل سلعته، فحلف بالله: لقد أعطى بها ما لم يعطها، فنزلت {إن الذين يشترون بعهد الله وأيمنهم ثمنا قليلا} [سورة آل عمران: ٧٧]. وقال ابن أبي أو فى: الناجش آكل ربا خائن.
Bukhari reported it in the Book of Testimonies (2675) from Ishaq, who said, Yazid bin Harun informed us, Awwam informed us, Ibrahim Abu Ismail Saksaki told me, he heard Abdullah bin Abu Awfa say, and then he related it.Najsh in language means driving game away and stirring it from its place so that it may be hunted. One says, "najashtu the game, anjushuhu" (with damma), "najshan."Malik said following the hadith, "Najsh is when you offer someone more than the price of his goods, while you have no intention of buying them, so that others follow your lead."Tirmidhi said, "Najsh is when a man who is not the owner of the goods comes to the owner and bids more than they are worth, doing this when a buyer is present, wanting to deceive the buyer through it. He has no intention of buying, but only wants to trick the buyer with what he bids." End of quote.As for the ruling on najsh, Shafii said, "The one who practices najsh is sinful for what he does, but the sale is valid, because the seller is not the one committing najsh." Tirmidhi mentioned this.