The Chapter of Siwak
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 12
وَقَالَ اَلْبَاقِرُ وَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «صَلاَةُ رَكْعَتَيْنِ بِسِوَاكٍ أَفْضَلُ مِنْ سَبْعِينَ رَكْعَةً بِغَيْرِ سِوَاكٍ.
Imam Muhammad ibn Ali Al-Baqir عليه السلام and Imam Jafar ibn Muhammad Al-Sadiq عليه السلام said: "Two units of prayer performed with siwak (tooth cleaning) are better than seventy units of prayer without siwak."
- Ṣaḥīḥ al-Faqīh