Vesālīsutta

sn54.9:6.1 Then the Buddha went to the assembly hall, sat down on the seat spread out,

sn54.9:6.2 and addressed the mendicants:

sn54.9:6.3 “Mendicants, when this immersion due to mindfulness of breathing is developed and cultivated it’s peaceful and sublime, a delectable and blissful meditation. And it disperses and settles unskillful qualities on the spot whenever they arise.