Musannaf Ibn Abi Shaybah 21408 — Sale by auction

Amr bin Muhajir said that Umar bin Abd al-Aziz sent Umayrah bin Yazid al-Filastini to sell captives by auction. When he had finished and came back, Umar asked him, "How was the sale today?" He said, "O Commander of the Believers, had I not gone in myself and raised the bidding, it would have been slack today." Umar asked him, "Were you merely raising the bidding, with no intention of buying?" He admitted it, so Umar (may Allah have mercy on him) said, "This is najash (false bidding), and it is not lawful. O Umayrah, send a crier to announce that the sale is void and that najash is not lawful."