Musnad Ahmad 937:78

Hajjaj narrated to us, Shaiban narrated to us, Mansur narrated to us, from Rib'i, from Kharasha ibn al-Hurr, from Abu Dharr, who said: When the Messenger of Allah (peace and blessings of Allah be upon him) would take to his bed at night, he would say: "O Allah, in Your name we die and we 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."