Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.4.17

3.3.4.17

atha subrahmaṇyāmāhvayati | yathā yebhyaḥ pakṣyantsyāttānbrūyādityahe vaḥ paktāsmītyevamevaitaddevebhyo yajñaṃ nivedayati subrahmaṇyo3ṃ subrahmṇyo3miti brahma hi devānpracyāvayati triṣkṛtva āha trivṛddhi yajñaḥ

Thereupon he recites the Subrahmanyâ litany. Even as one would say to those for whom he intends to prepare a meal, 'On such and such a day I will prepare a meal for you;' so does he thereby announce the sacrifice to the gods. 'Subrahmanyôm! Subrahmanyôm! Subrahmanyôm!' thus he calls, for the Brahman indeed moves the gods onward. Thrice he says it, because the sacrifice is threefold.