He said: 'Breath (prâna). For all these beings merge into breath alone, and from breath they arise. This is the deity belonging to the prastâva. If, without knowing that deity, you had sung forth your hymns, your head would have fallen off, after you had been warned by me.'

In plain words: Ushasti says the god is breath (prana), because all living beings come from breath and return into it. Singing without knowing this, after being warned, would have cost the priest his head.