Malik related to me that Yahya ibn Said heard Said ibn al-Musayyab say, "When Umar ibn al-Khattab came from Mina, he made hiscamel kneel at al-Abtah, and then he gathered a pile of small stonesand cast his cloak over them and dropped to the ground. Then he raisedhis hands to the sky and said, 'O Allah! I have become old and mystrength has weakened. My flock is scattered. Take me to You withnothing missed out and without having neglected anything.' Then hewent to Madina and addressed the people. He said, 'People! Sunan havebeen laid down for you. Obligations have been placed upon you. Youhave been left with a clear way unless you lead people astray rightand left.' He struck one of his hands on the other and then said,'Take care lest you destroy the ayat of stoning so that one will say,"We do not find two hadds in the Book of Allah." The Messenger ofAllah, may Allah bless him and grant him peace, stoned, so we havestoned. By He in Whose Hand my self is, had it not been that peoplewould say that Umar ibn al-Khattab has added to the Book of Allah ta-ala, we would have written it, "The full-grown man and the full-grownwoman, stone them absolutely." We have certainly recited that.'"Malik said, "Yahya ibn Said said Said ibn al-Musayyab said,'Dhu'l-Hijja had not passed before Umar was murdered, may Allah havemercy on him.' "Yahya said that he had heard Malik say, "Asfor his words 'The full-grown man and the full-grown woman' he meant,'The man and the woman who have been married, stone them absolutely.'"
USC-MSA web (English) reference: Book 41, Hadith 10
Arabic reference: Book 41, Hadith 1512