كتاب الفضائل
9
The Book of Virtues
Shuraih bin Hani (May Allah be pleased with him) reported:
I asked 'Aishah (may Allah be pleased with her): "What was the first thing which the Prophet (ﷺ) would do when he entered his house?" She replied: "He would use Miswak (tooth-stick)."

[Muslim].
وعن شريح بن هانئ قال‏:‏ قلت لعائشة، رضي الله عنها‏:‏ بأي شيء كان يبدأ النبي صلى الله عليه وسلم إذا دخل بيته‏.‏ قالت‏:‏ بالسواك‏.‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏
Sunnah.com reference : Book 9, Hadith 210
Arabic/English book reference : Book 9, Hadith 1200