عَنْ حُذَيْفَةَ بْنِ الْيَمَانِ رَضِيَ اللَّهُ عَنْهُ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ كَانَ إِذَا قَامَ مِنَ اللَّيْلِ (وَفِي رِوَايَةٍ: إِذَا قَامَ مِنَ التَّهَجُّدِ) يَشُوصُ فَاهُ بِالسِّوَاكِ
It is narrated from Sayyiduna Hudhayfah bin Yaman (may Allah be pleased with him) that when the Noble Prophet (peace and blessings be upon him) would wake up at night, and in one narration: when he would wake up for Tahajjud, he would clean his mouth with a miswak.