Sahih Bukhari Volume 008, Book 075, Hadith Number 336.

Narated By Hudhaifa : Whenever the Prophet intended to go to bed, he would recite: "Bismika Allahumma amutu wa ahya (With Your name, O Allah, I die and I live)." And when he woke up from his sleep, he would say: "Al-hamdu lil-lahil-ladhi ahyana ba'da ma amatana; wa ilaihi an-nushur (All the Praises are for Allah Who has made us alive after He made us die (sleep) and unto Him is the Resurrection)."