Bedtime adhkar: In Your Name my Lord, I lay myself down

بِاسْمِكَ رَبِّي وَضَعْتُ جَنْبِي، وَبِكَ أَرْفَعُهُ، فَإِنْ أَمْسَكْتَ نَفْسِي فَارْحَمْهَا، وَإِنْ أَرْسَلْتَهَا فَاحْفَظْهَا، بِمَا تَحْفَظُ بِهِ عِبَادَكَ الصَّالِحِينَ

Bismika rabbi wada'tu janbi, wa bika arfa'uhu, fa'in amsakta nafsi farhamha, wa in arsaltaha fahfadhha, bima tahfadhu bihi 'ibadakas-salihin

In Your Name my Lord, I lay myself down, and in Your Name I rise. And if You take my soul, have mercy on it, and if You send it back then protect it as You protect Your righteous slaves.

Ṣaḥīḥ al-Bukhārī 6320, Ṣaḥīḥ Muslim 2714 (wording varies slightly between narrations)