كتاب الطهارة
Read the English translation first, with the original Arabic directly underneath.
It was narrated that Anas bin Malik said:
"The Messenger of Allah (ﷺ) said: 'I have indeed urged you with regard to the Siwak.'"
قَدْ أَكْثَرْتُ عَلَيْكُمْ فِي السِّوَاكِ