Hadith on Sleep: Let him lie on his right side and say this

Abu Salih reported: The Prophet, peace and blessings be upon him, commanded us, when one intends to sleep, to lie on his right side and then say, “O Allah, Lord of the heavens and Lord of the earth, Lord of the Great Throne, our Lord and the Lord of all things, the Splitter of the grain and seed, the Revealer of the Torah, the Gospel, and the Criterion (the Quran), I seek refuge in you from the evil of everything whose forelock you hold. O Allah, you are the First, there is nothing before you. You are the Last, there is nothing after you. You are the Manifest, there is nothing above you. You are the Hidden, there is nothing beyond you. Relinquish my debts and enrich me from poverty.”

Source: Ṣaḥīḥ Muslim 2713

Grade: Sahih (authentic) according to Muslim

عن أبي صالح يَأْمُرُنَا النبي صلى الله عليه وسلم إِذَا أَرَادَ أَحَدُنَا أَنْ يَنَامَ أَنْ يَضْطَجِعَ عَلَى شِقِّهِ الْأَيْمَنِ ثُمَّ يَقُولُ اللَّهُمَّ رَبَّ السَّمَاوَاتِ وَرَبَّ الْأَرْضِ وَرَبَّ الْعَرْشِ الْعَظِيمِ رَبَّنَا وَرَبَّ كُلِّ شَيْءٍ فَالِقَ الْحَبِّ وَالنَّوَى وَمُنْزِلَ التَّوْرَاةِ وَالْإِنْجِيلِ وَالْفُرْقَانِ أَعُوذُ بِكَ مِنْ شَرِّ كُلِّ شَيْءٍ أَنْتَ آخِذٌ بِنَاصِيَتِهِ اللَّهُمَّ أَنْتَ الْأَوَّلُ فَلَيْسَ قَبْلَكَ شَيْءٌ وَأَنْتَ الْآخِرُ فَلَيْسَ بَعْدَكَ شَيْءٌ وَأَنْتَ الظَّاهِرُ فَلَيْسَ فَوْقَكَ شَيْءٌ وَأَنْتَ الْبَاطِنُ فَلَيْسَ دُونَكَ شَيْءٌ اقْضِ عَنَّا الدَّيْنَ وَأَغْنِنَا مِنْ الْفَقْرِ

2713 صحيح مسلم كتاب الذكر والدعاء والتوبة والاستغفار باب ما يقول عند النوم وأخذ المضجع