The Chapter of Siwak
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 12
وَقَالَ عَلَيْهِ اَلسَّلاَمُ: «لِكُلِّ شَيْءٍ طَهُورٌ وَ طَهُورُ اَلْفَمِ اَلسِّوَاكُ.
Imam Jafar ibn Muhammad Al-Sadiq عليه السلام said: "Everything has a means of purification, and the means of purification for the mouth is the siwak (tooth cleaning)."
- Ṣaḥīḥ al-Faqīh