Sunan Abi Da'ud

Narrated Zayd ibn Khalid al-Juhani: I heard the Messenger of Allah (ﷺ) say: Were it not hard on my ummah, I would order them to use the tooth-stick at the time of every prayer. AbuSalamah said: Zayd ibn Khalid used to attend the prayers in the mosque with his tooth-stick on his ear where a clerk carries a pen, and whenever he got up for prayer he used it.