Manusmriti

siva.sh/manusmriti/2/143

अग्न्याधेयं पाकयज्ञानग्निष्टोमादिकान् मखान् । यः करोति वृतो यस्य स तस्यर्त्विगिहोच्यते ॥ १४३ ॥

sanskrit

He who, being (duly) chosen (for the purpose), performs the Agnyadheya, the Pakayagnas, (and) the (Srauta) sacrifices, such as the Agnishtoma (for another man), is called (his) officiating priest.

english translation

agnyAdheyaM pAkayajJAnagniSTomAdikAn makhAn | yaH karoti vRto yasya sa tasyartvigihocyate || 143 ||

hk transliteration by Sanscript