1634An NasaiSahih (Darussalam)أَخْبَرَنَا أَحْمَدُ بْنُ سُلَيْمَانَ، قَالَ حَدَّثَنَا عُبَيْدُ اللَّهِ، قَالَ أَنْبَأَنَا إِسْرَائِيلُ، عَنْ أَبِي حَصِينٍ، عَنْ شَقِيقٍ، قَالَ كُنَّا نُؤْمَرُ إِذَا قُمْنَا مِنَ اللَّيْلِ أَنْ نَشُوصَ أَفْوَاهَنَا بِالسِّوَاكِ .It was narrated that Shaqiq said:"We were commanded, when we got up to pray at night, to clean our mouths with the siwak."Reference: Sunan an-Nasa'i 1624 In-book : Book 20, Hadith 27 English translation : Vol. 2, Book 20, Hadith 1625