From Sahih Bukhari (Hadith 6325):
Narrated Abu Dhar:Whenever the Prophet (ﷺ) lay on his bed, he used to say: "Allahumma bismika amutu wa ahya," and when he woke up he would say: "Al-hamdu lil-lahilladhi ahyana ba'da ma an atana, wa ilaihi an-nushur
Reference: Bukhari 6325