Śatapatha Brāhmaṇa ("of a hundred paths") 6.2.1.7

6.2.1.7

sa aikṣata | yā vai śrīrabhyadhāsiṣamimāstāḥ śīrṣasu hanta śīrṣāṇyevopadadhā iti sa śīrṣāṇyevotkṛtyopādhattāthetarāṇi kusindhānyapsu prāplāvayadajena yajñaṃ samasthāpayannenme yajño vikṛṣṭo 'sadityātmā vai yajño nenme 'yamātmā vikṛṣṭo 'sadityetena paśuneṣṭvā tatprajāpatirapaśyadyathaitasyāgnerantaṃ na paryait

He considered, 'Those glories (signs of excellence) upon which I have set my mind are contained in the heads: well then, I will only put on the heads.' He cut off the heads and put them on (himself, or the altar). The remaining trunks he then let float on the water, and brought the sacrifice to its completion by means of (the offering of) a he-goat, thinking, 'Lest my sacrifice be pulled to pieces.' After performing that animal sacrifice, Pragâpati saw that he had not yet reached the end of Agni (the fire-altar).