Shaddad b. Aus reported God’s messenger as saying, "If any Muslim recites a <i>sura</i> from God’s Book when he goes to bed, God will put an angel in charge of him, and nothing which may harm him will come near him till he wakes". Tirmidhi transmitted it.

وَعَنْ شَدَّادِ بْنِ أَوْسٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسلم: «مَا من مُسْلِمٍ يَأْخُذُ مَضْجَعَهُ بِقِرَاءَةِ سُورَةٍ مِنْ كِتَابِ اللَّهِ إِلَّا وَكَّلَ اللَّهُ بِهِ مَلَكًا فَلَا يَقْرَبُهُ شَيْءٌ يُؤْذِيهِ حَتَّى يَهُبَّ مَتَى هَبَّ» . رَوَاهُ التِّرْمِذِيّ