Abu Dawud Book 1, Hadith Number 49.

Chapter : How to use the toothstick.

Narated By Abu Burdah on the authority of his father Abu Musa al-Ashari according to the version of Musaddad : We came to the Apostle of Allah (PBUH) to provide us with a mount, and found him using the tooth-stick, its one end being at his tongue (i.e. he was rinsing his mouth).

According to the version of Sulaiman it goes: I entered upon the Prophet (PBUH) who was using the tooth-stick and had placed it at one side of his tongue, producing a gurgling sound.

Abu Dawud said: Musaddad said that the tradition was lengthy but he shortened it.