Musnad Ahmad 1034:150

Sulayman ibn Hayyan narrated to us, Sufyan informed 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 take to his bed, he would say: "O Allah, in Your name I live and I die." 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."