Śatapatha Brāhmaṇa ("of a hundred paths") 7.4.2.33

7.4.2.33

sā yadaṣāḍhā nāma | devāścāsurāścobhaye prājāpatyā aspardhanta te devā etāmiṣṭakāmapaśyannaṣāḍhāmimāmeva tāmupādadhata tāmupadhāyāsurāntsapatnānbhrātṛvyānasmātsarvasmādasahanta yadasahanta tasmādaṣāḍhā tathaivaitadyajamāna etāmupadhāya diṣantam bhrātṛvyamasmātsarvasmātsahate

And as to its being called Ashâdhâ. The gods and the Asuras, both of them sprung from Pragâpati, strove together. The gods saw this invincible brick, even this earth; they put it on (the altar); and having put it on, they conquered (and drove) the Asuras, the enemies, the rivals, from this universe; and inasmuch as (thereby) they conquered (asahanta), it is called Ashâdhâ. In like manner the Sacrificer, after putting on that (brick), conquers (and drives) his spiteful rival from this universe (or, from everything here).