Musannaf Ibn Abi Shayba 19:708

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Ash'ath, from Ali ibn Zayd, from Yusuf ibn Mahran, from Ibn Abbas, who said: Umar said: "Stoning is a prescribed punishment from the punishments of Allah, so do not be deceived regarding it." And he said: "That is because the Messenger of Allah (peace be upon him) stoned, and Abu Bakr stoned, and I stoned."