Sahih Muslim 2028
Sahih Muslim · Book 36: The Book of Drinks · It is disliked to breathe into the vessel, and it is recommended to take three breaths, outside the vessel
وَحَدَّثَنَاهُ قُتَيْبَةُ بْنُ سَعِيدٍ ، وَأَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ قَالاَ حَدَّثَنَا وَكِيعٌ ، عَنْ هِشَامٍ، الدَّسْتَوَائِيِّ عَنْ أَبِي عِصَامٍ ، عَنْ أَنَسٍ ، عَنِ النَّبِيِّ صلى الله عليه وسلم بِمِثْلِهِ وَقَالَ فِي الإِنَاءِ .
This hadith is reported on the authority of Anas with a slight variation of wording.