Musnad Ahmad 31:658

Surayj narrated to us, Hammad narrated to us, from Hammad, from Ibrahim, from Abu Sa’id al-Khudri, that the Messenger of Allah (peace and blessings of Allah be upon him) forbade hiring a worker until his wage is clarified. He also forbade *al-najash* (bidding up the price without the intention to buy), *al-lams* (a form of pre-Islamic sale involving touching the garment), and *ilqa’ al-hajar* (a form of pre-Islamic sale involving throwing a stone).