Sunan Ibn Majah
290
Sahih+3

It was narrated from Miqdam bin Shuraih bin Hani' that his father said:"I said to 'Aishah: 'Tell me, what was the first thing that the Messenger of Allah did when he entered upon you?' She said: 'The first thing he would do would be to use the tooth stick

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi