Ashtangasamgraha 30.11

30.11

Now, the person fit for smoking, cheerful, seated upright, having previously inhaled and exhaled, with lips and teeth open, eyes fixed on the tip of the pipe, should close one nostril after another, draw in through the other, and discharge through the mouth.

Through the mouth, however, [one should draw in] only through the mouth,

not through the nose, for fear of injury to sight.