Musnad Ahmad 1034:128

'Abd al-Rahman narrated to us, from Sufyan, from 'Abd al-Malik ibn 'Umayr, from Rib'i ibn Hirash, from Hudhayfah, who said: When the Prophet, peace and blessings of Allah be upon him, would go to his bed, he would say: "O Allah, in Your name I die, and in Your name 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."