Musaddad said, "We came to the Messenger of Allah ﷺ to ask him for mounts, and I saw him brushing his tongue with the siwak."
حدثنا مسدد وسليمان بن داود العتكي قالا حدثنا حماد بن زيد عن غيلان بن جرير
مسدد قال أتينا رسول الله ﷺ نستحمله فرأيته يستاك على لسانه
No references are available.
Bukhari reported it in the Book of Wudu, Chapter on the tooth-stick, Hadith: 244, and Muslim in the Book of Purification, Chapter on the tooth-stick, Hadith: 254, from the hadith of Hammad bin Zayd, through the same chain. Nasai also reported it, Hadith: 3.