Siwak (to clean the teeth with Siwak which is a tooth-brush in the form of a pencil from the roots of the Arak tree)

Narrated Abu Burda:

My father said, "I came to the Prophet (ﷺ) and saw him carrying a Siwak in his hand and cleansing his teeth, saying, 'U' U'," as if he was retching while the Siwak was in his mouth."