Musnad Ahmad 1034:32

Waki' narrated to us, Sufyan narrated to us, from 'Abd al-Malik ibn 'Umayr, from Rib'i ibn Hirash, from Hudhayfah, who said: When the Messenger of Allah (peace and blessings of Allah be upon him) would go to his bed, he would say: "In Your name, O Allah, I die and I live." And when he would wake up, he would say: "Praise be to Allah, who gave us life after He caused us to die, and to Him is the resurrection."