Ablutions (Wudu')
4/73. Chapter:
Siwak (to clean the teeth with Siwak which is a tooth-brush in the form of a pencil from the roots of the Arak tree
وَقَالَ ابْنُ عَبَّاسٍ بِتُّ عِنْدَ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَاسْتَنَّ.Ibn ‘Abbas said, “Once I passed the night with the Prophet ﷺ and saw him cleaning his teeth (with Siwak).”
Sahih Bukhari
حَدَّثَنَا عُثْمَانُ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، قَالَ كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا قَامَ مِنَ اللَّيْلِ يَشُوصُ فَاهُ بِالسِّوَاكِ.
Narrated Hudhaifa: Whenever the Prophet (ﷺ) got up at night, he used to clean his mouth with Siwak.
Reference : Sahih al-Bukhari 245In-book reference : Book 4, Hadith 111USC-MSA web (English) reference : Vol. 1, Book 4, Hadith 246