Musnad Ahmad 28:127

Hassan narrated to us, Ibn Lahi'ah narrated to us, Huyayy ibn Abdullah narrated to me, that Abu Abd al-Rahman narrated to him, from Abdullah ibn Amr, that the Messenger of Allah (peace and blessings of Allah be upon him) mentioned the testers of the graves. Umar said: "Will our intellects be returned to us, O Messenger of Allah?" The Messenger of Allah (peace and blessings of Allah be upon him) said: "Yes, like your state today." Umar said: "May a stone be in his mouth."