Riyad as-Salihin 15:51

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

The Messenger of Allah (ﷺ) used to supplicate when he went to bed at night: "Bismik-Allahumma ahya wa amut (With Your Name, O Allah, I expire and return to life)." [Al- Bukhari] .