(73) باب السِّوَاكِ
Narrated Hudhaifa:
Whenever the Prophet (ﷺ) got up at night, he used to clean his mouth with Siwak.
Reference: Sahih al-Bukhari 245
In-book reference: Book 4, Hadith 112
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 4, Hadith 246