Śatapatha Brāhmaṇa ("of a hundred paths") 9.4.4.8

9.4.4.8

atha rājānamabhiṣutyāgnau juhoti | eṣa vai sa sava etadvai tatsūyate yamasmai tametā devatāḥ savamanumanyante yābhiranumataḥ sūyate yasmai vai rājāno rājyamanumanyante sa rājā bhavati na sa yasmai na tadyadagnau juhoti tadagnimabhiṣiñcati so 'syaiṣa daiva ātmā somābhiṣikto bhavatyamṛtābhiṣikto 'tha bhakṣayati tadātmānamabhiṣiñcati so 'syāyamātmā somābhiṣikto bhavatyamṛtābhiṣiktaḥ

And when he has pressed the king (Soma) he offers in the fire. This, indeed, is that very rite of consecration (or pressing)--and by that he is now consecrated (or pressed)--which this (Sacrificer) is permitted to perform by those deities with whose permission he is consecrated; for he alone becomes king whom the (other) kings allow (to assume) the royal dignity, and not he whom (they do) not (allow to assume it). Now when he offers in the fire he thereby consecrates (anoints) Agni, and that divine body of his, being consecrated by Soma, becomes consecrated by the nectar of immortality. And he himself drinks (thereof): he thereby consecrates himself, and this self (body) of his, being consecrated by Soma, becomes consecrated by the nectar of immortality.