Sahih al-Bukhari 5631
صحيح البخاري#5631Sahihحَدَّثَنَا أَبُو عَاصِمٍ، وَأَبُو نُعَيْمٍ قَالاَ حَدَّثَنَا عَزْرَةُ بْنُ ثَابِتٍ، قَالَ أَخْبَرَنِي ثُمَامَةُ بْنُ عَبْدِ اللَّهِ، قَالَ كَانَ أَنَسٌ يَتَنَفَّسُ فِي الإِنَاءِ مَرَّتَيْنِ أَوْ ثَلاَثًا، وَزَعَمَ أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَتَنَفَّسُ ثَلاَثًا.
Narrated Thumama bin `Abdullah:Anas used to breathe twice or thrice in the vessel (while drinking) and used to say that the Prophet; used to take three breaths while drinking
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:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 74:57