Sunan an-Nasa'i 2

سنن النسائي#2Sahih

أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، وَقُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ جَرِيرٍ، عَنْ مَنْصُورٍ، عَنْ أَبِي وَائِلٍ، عَنْ حُذَيْفَةَ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا قَامَ مِنَ اللَّيْلِ يَشُوصُ فَاهُ بِالسِّوَاكِ ‏.‏

It was narrated that Huthaifah said:"When the Messenger of Allah (ﷺ) got up at night, he would brush his mouth with the Siwak

Scholarly Authentication

We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:

Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon

In-book reference: 1:2