Al-Kāfi - Volume 3 > Brushing One’s Teeth
Hadith #4

4ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنِ ابْنِ بُكَيْرٍ عَمَّنْ ذَكَرَهُ عَنْ أَبِي جَعْفَرٍ (عَلَيْهِ الْسَّلام) فِي السِّوَاكِ قَالَ لاَ تَدَعْهُ فِي كُلِّ ثَلاَثٍ وَلَوْ أَنْ تُمِرَّهُ مَرَّةً.

4. Ali ibn Ibrahim has narrated from his father from ibn abu ‘Umayr from ibn Bukayr from those whom he has mentioned has said the following: “Abu Ja’far, ‘Alayhi al-Salam, has said, ‘You must not neglect brushing after every third (Salah (prayer)) even though it is a light one (brushing).”’