Riyad as-Salihin 15:39

Hudhaifah and Abu Dharr (May Allah be pleased with him) reported:

Whenever the Messenger of Allah (ﷺ) went to bed, he would supplicate: "Bismika-Allahumma amut wa ahya (With Your Name, O Allah, I die and return to life)"; and when he woke up, he would supplicate thus: "Al-hamdu lillahilladhi ahyana ba'da ma amatana, wa ilaihin-nushur (All praise belongs to Allah Who has restored us back to life after causing us to die; and to Him shall we return)." [Al-Bukhari]