(9) باب طُولِ الْقِيَامِ فِي صَلاَةِ اللَّيْلِ
Narrated Hudhaifa:
Whenever the Prophet (ﷺ) got up for Tahajjud prayer he used to clean his mouth (and teeth) with Siwak. (IT)
Reference (IT): Sahih al-Bukhari 1136 (IT)
In-book reference (IT): Book 19, Hadith 17 (IT)
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 21, Hadith 237 (IT)