From Sahih Bukhari (Hadith 6314):
Narrated Hudhaifa:When the Prophet (ﷺ) went to bed at night, he would put his hand under his cheek and then say, "Allahumma bismika amutu wa ahya," and when he got up, he would say, "Al-Hamdu lil-lahi al-ladhi ahyana ba'da ma amatana, wa ilaihi an-nushur
Reference: Bukhari 6314