Chandogya Upanishad 1.11

Then the sacrificer said to him: 'I should like to know who you are, Sir.' He replied: 'I am Ushasti Kâkrâyana.'

He said: 'I looked for you, Sir, for all these sacrificial offices, but not finding you, I chose others.'

'But now, Sir, take all the sacrificial offices.' Ushasti said: "Very well; but let those, with my permission, perform the hymns of praise. Only as much wealth as you give to them, so much give to me also.' The sacrificer assented.

Then the Prastotri approached him, saying: 'Sir, you said to me, "Prastotri, if you, without knowing the deity which belongs to the prastâva, are going to sing it, your head will fall off,"—which then is that deity?'

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.'

Then the Udgâtri approached him, saying: 'Sir, you said to me, "Udgâtri, if you, without knowing the deity which belongs to the udgîtha, are going to sing it, your head will fall off,"—which then is that deity?'

He said: 'The sun (âditya). For all these beings praise the sun when it stands on high. This is the deity belonging to the udgîtha. If without knowing that deity, you had sung out your hymns, your head would have fallen off, after you had been warned by me.'

Then the Pratihartri approached him, saying: 'Sir, you said to me, "Pratihartri, if you, without knowing the deity belonging to the pratihâra, are going to sing it, your head will fall off,"—which then is that deity?'

He said: 'Food (anna). For all these beings live when they partake of food. This is the deity belonging to the pratihâra. If, without knowing that deity, you had sung your hymns, your head would have fallen off, after you had been warned by me.'