Śatapatha Brāhmaṇa ("of a hundred paths") 5.2.3.1

5.2.3.1

pūrṇāhutiṃ juhoti | sarvaṃ vai pūrṇaṃ sarvam parigṛhya sūyā iti tasyāṃ varaṃ dadāti sarvaṃ vai varaḥ sarvam parigṛhya sūyā iti sa yadi kāmayeta juhuyādetāṃ yadyu kāmayetāpi nādriyeta

He offers a full-offering; for the full means the All: 'May I be consecrated after encompassing the All!' thus he thinks. At this (offering) he bestows a boon; for a boon means all: 'Having encompassed the All (the universe), may I be consecrated! thus he thinks. He may perform this offering, if he chooses; or, if he chooses, he may disregard it.