Purification (Kitab Al-Taharah)
1/30. Chapter:
Using The Siwak When Praying The (Voluntary) Night Prayer
Sunan Abi Dawud
حَدَّثَنَا مُحَمَّدُ بْنُ كَثِيرٍ، حَدَّثَنَا سُفْيَانُ، عَنْ مَنْصُورٍ، وَحُصَيْنٍ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا قَامَ مِنَ اللَّيْلِ يَشُوصُ فَاهُ بِالسِّوَاكِ .
Narrated Hudhaifah: When the Apostle of Allaah (sal Allaahu alayhi wa sallam) got up during the night (to pray), he cleansed his mouth with the tooth-stick.
Reference : Sunan Abi Dawud 55In-book reference : Book 1, Hadith 55English translation : Book 1, Hadith 54