Musnad Ahmad 1022:2

Al-Zubayri Muhammad ibn Abdullah narrated to us, Isra'il narrated to us, from Simak, who said: Abd al-Aziz ibn Abdullah ibn Amir narrated to me, [and] he narrated to me from one who heard the Prophet, may Allah bless him and grant him peace, when he ordered the stoning of a man between Makkah and Madinah. When he felt the [impact of the] stones, he went out and fled. The Prophet, may Allah bless him and grant him peace, said: "Why did you not leave him?"