Sahih Bukhari Volume 8, Book 80, Hadith 6326

حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا سُفْيَانُ، عَنْ عَبْدِ الْمَلِكِ بْنِ عُمَيْرٍ، عَنْ رِبْعِيِّ بْنِ حِرَاشٍ، عَنْ حُذَيْفَةَ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا أَرَادَ أَنْ يَنَامَ قَالَ ‏"‏ بِاسْمِكَ اللَّهُمَّ أَمُوتُ وَأَحْيَا ‏"‏‏.‏ وَإِذَا اسْتَيْقَظَ مِنْ مَنَامِهِ قَالَ ‏"‏ الْحَمْدُ لِلَّهِ الَّذِي أَحْيَانَا بَعْدَ مَا أَمَاتَنَا، وَإِلَيْهِ النُّشُورُ ‏"‏‏.‏

Narrated 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)."