The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
20/10. Chapter:
Using siwak when getting up to pray at night
Sunan an-Nasai
أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، عَنْ عَبْدِ الرَّحْمَنِ، عَنْ سُفْيَانَ، عَنْ مَنْصُورٍ، وَالأَعْمَشِ، وَحُصَيْنٍ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ إِذَا قَامَ مِنَ اللَّيْلِ يَشُوصُ فَاهُ بِالسِّوَاكِ .
It was narrated from Hudhaifah that: When the Prophet (ﷺ) got up to pray at night, he would brush his teeth with the siwak.
Reference : Sunan an-Nasa'i 1621In-book reference : Book 20, Hadith 24English translation : Vol. 2, Book 20, Hadith 1622