Srimad-Bhagavatam: Canto 2 - Chapter 1 - Verse 25

Sanskrit:

वस्तून्योषधय: स्‍नेहा रसलोहमृदो जलम् ।ऋचो यजूंषि सामानि चातुर्होत्रं च सत्तम ॥ २५ ॥

ITRANS:

vastūny oṣadhayaḥ snehārasa-loha-mṛdo jalamṛco yajūṁṣi sāmānicātur-hotraṁ ca sattama

Translation:

Other requirements are utensils, grains, clarified butter, honey, gold, earth, water, the Ṛg Veda, Yajur Veda and Sāma Veda and four priests to perform the sacrifice.

Purport:

To perform a sacrifice successfully, at least four expert priests are needed: one who can offer (hotā), one who can chant (udgātā), one who can kindle the sacrificial fire without the aid of separate fire (adhvaryu), and one who can supervise (brahmā). Such sacrifices were conducted from the birth of Brahmā, the first living creature, and were carried on till the reign of Mahārāja Yudhiṣṭhira. But such expert brāhmaṇa priests are very rare in this age of corruption and quarrel, and therefore in the present age only the yajña of chanting the holy name of the Lord is recommended. The scriptures enjoin: