Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.3.19

2.3.3.19

sapta ca vai śatānyaśītīnāmṛcaḥ | viṃśatiśca sa yatsāyam prātaragnihotraṃ juhoti te dve āhutī tā asya saṃvatsara āhutayaḥ sampadyante

Seven hundred and twenty eighties of Rik-verses (he should recite at the Agnihotra in the course of a year). When he offers the Agnihotra in the morning and evening, then there are two libations: hence those libations of his, in the course of a year, amount to--