Your mouths are pathways for the Quran, so freshen them with the siwak.
حدثنا محمد بن عبد العزيز حدثنا مسلم بن إبراهيم حدثنا بحر بن كنيز عن عثمان بن ساج عن سعيد بن جبير
إن أفواهكم طرق للقرآن فطيبوها بالسواك
No references are available.
[Its chain is daif] Isbahani narrated it in al-Hilyah, 4/296, from the hadith of Muslim bin Ibrahim, with this wording, as a raised hadith. Busiri graded it daif, since Bahr is daif (Taqrib), and it contains another flaw. It has a daif corroborating narration, see Talkhis Habir, 1/70, part 6/9.