Musnad Ahmad 1024:1

Sufyan narrated to us, saying: "O people, do not kill one another when you stone the Jamrah, and stone it with pebbles the size of those used for throwing (al-khadhf)." And its chain of narration was read to him: Yazid, from Sulayman ibn Amr ibn al-Ahwas, from his mother, meaning from the Prophet, peace and blessings of Allah be upon him.