The Messenger of Allah ﷺ said, "I have urged you repeatedly concerning the use of the siwak."
حدثنا عبد الصمد حدثنا أبي وعفان حدثنا عبد الوارث حدثنا شعيب يعني ابن الحبحاب
قال رسول الله ﷺ أكثرت عليكم في السواك
No references are available.
Its isnad is sahih. Shuayb bin Habhab Azdi Abu Salih is trustworthy. The hadith was narrated by Bukhari 2/5 in "The Book of Friday Prayer," chapter "The Tooth-stick on Friday," and Darimi 1/184, no. 681, in "The Book of Purification," chapter "The Tooth-stick," and Bayhaqi 1/35 with similar wording.