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. (Using translation from Abū Dāʾūd 55)
أَنَّ النَّبِيَّ ﷺ كَانَ «إِذَا قَامَ مِنَ اللَّيْلِ يَشُوصُ فَاهُ بِالسِّوَاكِ»