Musnad Ahmad 282:1

Ibn Fudayl narrated to us, from Yazid, from Sulayman ibn ‘Amr ibn al-Ahwas, from his mother, who said: I saw the Messenger of Allah (peace and blessings of Allah be upon him) stoning the Jamrat al-‘Aqabah from the bottom of the valley on the Day of Sacrifice, and he was saying: "O people, do not kill one another, and do not strike one another. And when you stone the Jamrah, stone it with pebbles the size of those used for throwing (al-khadhf)." He then threw seven pebbles and did not stop. Behind him was a man shielding him. I asked, "Who is this?" They said, "Al-Fadl ibn al-‘Abbas."