Musnad Ahmad 2:168

Yahya narrated to us, from Yahya, who said: I heard Sa’id ibn al-Musayyib [saying] that ‘Umar said: Beware of perishing regarding the verse of stoning, and that a speaker might say: "We do not find two prescribed punishments in the Book of Allah." For I have seen the Prophet, peace and blessings of Allah be upon him, stone, and we have stoned [after him].