The Chapter of Siwak
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 12
وَقَالَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «لَمَّا دَخَلَ اَلنَّاسُ فِي اَلدِّينِ أَفْوَاجاً أَتَتْهُمُ اَلْأَزْدُ أَرَقَّهَا قُلُوباً وَ أَعْذَبَهَا أَفْوَاهاً فَقِيلَ يَا رَسُولَ اَللَّهِ، هَذَا أَرَقُّهَا قُلُوباً عَرَفْنَاهُ فَلِمَ صَارَتْ أَعْذَبَهَا أَفْوَاهاً فَقَالَ «إِنَّهَا كَانَتْ تَسْتَاكُ فِي اَلْجَاهِلِيَّةِ.
Imam Jafar ibn Muhammad Al-Sadiq عليه السلام said : "When people entered the religion in large numbers, the tribe of Azd came among them with the softest hearts and the sweetest mouths. It was asked: 'O’ Messenger of Allah صلى الله عليه وعلى آله وسلم, we understand why they have the softest hearts, but why do they have the sweetest mouths?' He صلى الله عليه وعلى آله وسلم said: 'They used to use siwak (toothstick) even in the pre-Islamic period.'"
- Ṣaḥīḥ al-Faqīh