Śatapatha Brāhmaṇa ("of a hundred paths") 8.1.4.4

8.1.4.4

tadāhuḥ | yatpūrveṣu gaṇeṣvekaikaṃ stomamekaikam pṛṣṭhamupadadhātyatha kasmādatra dvau stomau dve pṛṣṭhe upadadhātītyātmā vā asyaiṣa ātmānaṃ tadaṅgānāṃ jyeṣṭhaṃ variṣṭhaṃ vīryavattamaṃ karoti tasmādayamātmāṅgānāṃ jyeṣṭho variṣṭho vīryavattamaḥ

Here now they say, 'Whereas in the first (four) sets he lays down a single stoma and a single prishtha each time, why, then, does he lay down here (in the centre) two stomas and two prishthas?' Well, this (central set) is his (Agni's) body: he thus makes the body (trunk) the best, the largest, the most vigorous of limbs; whence that body is the best, the largest, and most vigorous of limbs.