Abu Hurairah reported the Messenger of Allah ﷺ as saying:
when any of you goes to his bed, he should dust his bedding with the inner extremity of his lower garment, for he does not know what has come on it since he left it. He should then lie down on his right side and say: In Thy name, my mercy on it, but if Thou lettest it go, guard it with that which Thou guardest Thy upright servants.

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عُمَرَ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ﷺ " إِذَا أَوَى أَحَدُكُمْ إِلَى فِرَاشِهِ فَلْيَنْفُضْ فِرَاشَهُ بِدَاخِلَةِ إِزَارِهِ فَإِنَّهُ لاَ يَدْرِي مَا خَلَفَهُ عَلَيْهِ ثُمَّ لْيَضْطَجِعْ عَلَى شِقِّهِ الأَيْمَنِ ثُمَّ لْيَقُلْ بِاسْمِكَ رَبِّي وَضَعْتُ جَنْبِي وَبِكَ أَرْفَعُهُ إِنْ أَمْسَكْتَ نَفْسِي فَارْحَمْهَا وَإِنْ أَرْسَلْتَهَا فَاحْفَظْهَا بِمَا تَحْفَظُ بِهِ عِبَادَكَ الصَّالِحِينَ " .