It is disliked to breathe into the vessel, and it is recommended to take three breaths, outside the vessel
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا عَبْدُ الْوَارِثِ بْنُ سَعِيدٍ، ح وَحَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنْ أَبِي عِصَامٍ، عَنْ أَنَسٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَتَنَفَّسُ فِي الشَّرَابِ ثَلاَثًا وَيَقُولُ " إِنَّهُ أَرْوَى وَأَبْرَأُ وَأَمْرَأُ " . قَالَ أَنَسٌ فَأَنَا أَتَنَفَّسُ فِي الشَّرَابِ ثَلاَثًا .
Anas reported that Allah's Messenger (ﷺ) breathed three times (outside the vessel) in the course of a drink and said: It is more thirst- quenching, healthier and more wholesome. Anas said: So I also breathe three times in the course of a drink.