Musannaf Ibn Abi Shayba 13:3185

Abu Bakr narrated to us, he said: Ibn ‘Uyaynah narrated to us, from Hisham ibn Hujayr, from Iyas ibn Mu‘awiyah, regarding a man who was bargaining with another man, and he wanted to bargain with him, so the bargained-with man died. ‘Umar ibn al-Khattab viewed it as a partnership.