وَعَنْ أَنَسٍ عَنِ
النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مِنْ أَرَادَ أَنْ يَنَامَ عَلَى فِرَاشِهِ فَنَامَ عَلَى يَمِينِهِ ثُمَّ قَرَأَ مِائَةَ مَرَّةٍ (قل هُوَ الله أحد) إِذا كَانَ يَوْم الْقِيَامَةِ يَقُولُ لَهُ الرَّبُّ: يَا عَبْدِي ادْخُلْ عَلَى يَمِينِكَ الْجَنَّةَ»
He reported the Prophet (sallallahu alayhi wa sallam) as saying, “If anyone who is about to sleep on his bed lies on his right side, then recites ‘Say, He is God, One’ a hundred times, the Lord will say to him on the day of resurrection, ‘My servant, enter paradise to your right’.” Tirmidhi transmitted it, saying this is a hasan gharib tradition.
Mishkat al-Masabih 2063, Book 9, The Excellent Qualities of the Qur'an, Hadith 49. 1 min read