Sahih Muslim 238
Sahih Muslim · Book 2: The Book of Purification · Odd numbers when rinsing the nose and cleaning oneself with pebbles (istijmar)
Abu Huraira reported:
حَدَّثَنِي بِشْرُ بْنُ الْحَكَمِ الْعَبْدِيُّ ، حَدَّثَنَا عَبْدُ الْعَزِيزِ، - يَعْنِي الدَّرَاوَرْدِيَّ - عَنِ ابْنِ الْهَادِ ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ ، عَنْ عِيسَى بْنِ طَلْحَةَ ، عَنْ أَبِي هُرَيْرَةَ ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " إِذَا اسْتَيْقَظَ أَحَدُكُمْ مِنْ مَنَامِهِ فَلْيَسْتَنْثِرْ ثَلاَثَ مَرَّاتٍ فَإِنَّ الشَّيْطَانَ يَبِيتُ عَلَى خَيَاشِيمِهِ " .
The Apostle of Allah (ﷺ) said. When any one of you awakes up from sleep and performs ablution, he must clean his nose three times, for the devil spends the night in the interior of his nose.