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.