We were instructed that whenever we got up at night, we should clean our mouths with the siwak.
أخبرنا أحمد بن سليمان قال حدثنا عبيد الله قال أنبأنا إسرائيل عن أبي حصين
كنا نؤمر إذا قمنا من الليل أن نشوص أفواهنا بالسواك
[sahih, mawquf] and it was previously mentioned, no. 2 Ubaydullah is Ibn Musa, and Hafiz said in Nukat Ziraf*, 3336, the mention of Huzaifa was omitted in Nasai's version from the narration of Israil alone.