Śatapatha Brāhmaṇa ("of a hundred paths") 3.6.1.18

3.6.1.18

atha paryṛṣati | brahma dṛṃha kṣatraṃ dṛṃhāyurdṛṃha prajāṃ dṛṃhetyāśīrevaiṣaitasya karmaṇa āśiṣamevaitadāśāste samambhūmi paryarṣaṇaṃ karoti gartasya vā uparibhūmyathaivaṃ devatrā tathā hāgartamidbhavati

He then presses it firmly all round, with, 'Uphold thou the priesthood! uphold the nobility, uphold our life, uphold our progeny!' this is the blessing of this rite: that blessing he thereby invokes. He presses it so as to be level with the ground: with an (ordinary) hole (round trees for watering) it is higher than the ground, but in this way it is with the gods;--and thus it is not planted in an (ordinary) hole.