'Umar bin al-Khattab (RAA) narrated that he addressed the people and said, 'Verily Allah has sent Muhammad with the Truth and sent down the Book to him, and the verse of stoning was included in what Allah sent down. We recited, memorized and comprehended it. The Messenger of Allah (ﷺ) accordingly (to what was in the verse) stoned to death (whoever committed adultery while being married), and we stoned after his death. But I am afraid that after a long time passes, someone may say, 'We do not find the Verses of stoning in Allah's Book, and thus they may go astray by abandoning an obligation that Allah has sent down. Verily, stoning is an obligation in the Book of Allah to be inflicted on married men and women who commit adultery, when their crime is proven, evident by pregnancy, or through the confession (of the adulterer).' Agreed upon.
English reference: Book 10, Hadith 1248
Arabic reference: Book 10, Hadith 1209