Sunan an-Nasa'i 8
سنن النسائي#8Sahihأَخْبَرَنَا عَلِيُّ بْنُ خَشْرَمٍ، قَالَ حَدَّثَنَا عِيسَى، - وَهُوَ ابْنُ يُونُسَ - عَنْ مِسْعَرٍ، عَنِ الْمِقْدَامِ، - وَهُوَ ابْنُ شُرَيْحٍ - عَنْ أَبِيهِ، قَالَ قُلْتُ لِعَائِشَةَ بِأَىِّ شَىْءٍ كَانَ يَبْدَأُ النَّبِيُّ صلى الله عليه وسلم إِذَا دَخَلَ بَيْتَهُ قَالَتْ بِالسِّوَاكِ .
It was narrated from Al-Miqdam - Abu Shuraih - that his father said:"I said to 'Aishah: 'What did the Prophet (ﷺ) start with when he entered his house?' She said: 'The Siwak
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 1:8