Śatapatha Brāhmaṇa ("of a hundred paths") 1.1.3.9

1.1.3.9

yūyamindramavṛṇīdhvaṃ vṛtratūrya iti | etā u hīndramavṛṇata vṛtreṇa spardhamānametābhirhyenamahaṃstasmādāha yūyamindramavṛṇīdhvaṃ vṛtratūrya 'iti

'You chose Indra in the battle against Vritra!' for they, too, chose Indra when he was battling with Vritra, and with them he killed him: therefore he says, 'You chose Indra in the battle against Vritra!'