Śatapatha Brāhmaṇa ("of a hundred paths") 1.3.5.3

1.3.5.3

tadu haika āhuḥ | agnaye samidhyamānāya hotaranubrūhīti tadu tathā na brūyādahotā vā eṣa purā bhavati yadaivainam pravṛṇīte 'tha hotā tasmādu brūyādagnaye samidhyamānāyānubrūhītyeva

Here now some people say, 'O Hotar, recite to the fire as it is being kindled!' But let him not say so; for that (priest) is not a Hotri as yet; only when he (the sacrificer) elects him, does he become a Hotri. Let him therefore say, 'Recite to the fire as it is being kindled!'