Musnad Abu Ya'la al-Mawsili 3:281

Muhammad ibn al-Muthanna narrated to us, Ubayd Allah ibn Musa narrated to us, al-Rabi’ ibn Habib informed me, from Nawfal ibn Abd al-Malik, from his father, from Ali, who said: The Messenger of Allah (peace and blessings of Allah be upon him) forbade bargaining before the rising of the sun, and he forbade the slaughtering of milk-producing animals.