Al-Kāfi

Hadith 1567
health-hygiene
عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ الْأَشْعَرِيِّ عَنِ ابْنِ الْقَدَّاحِ عَنْ أَبِي عَبْدِ اللَّهِ ( عليه السلام ) قَالَ قَالَ النَّبِيُّ ( صلى الله عليه وآله ) تَخَلَّلُوا فَإِنَّهُ يُنَقِّي الْفَمَ وَ مَصْلَحَةٌ لِلِّثَةِ .
6. A group of our companions narrated from Sahl ibn Ziyad, from Ja'far ibn Muhammad al-Ash'ari, from Ibn al-Qaddah, from Abu Abdullah (a.s.), who said: "The Prophet (s.a.w.) said: 'Use a toothpick, for it cleans the mouth and is beneficial for the gums.'"
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī