Śatapatha Brāhmaṇa ("of a hundred paths") 10.2.3.11

10.2.3.11

athāgnervidhāḥ aṣṭāviṃśatiḥ prāñcaḥ puruṣā aṣṭāviṃśatistiryañcaḥ sa ātmā caturdaśa puruṣā dakṣiṇaḥ pakṣaścaturdaśottaraścaturdaśa pucaṃ caturdaśāratnīndakṣiṇe pakṣa upadadhāti caturdaśottare caturdaśa vitastīḥ puca iti nvaṣṭānavateḥ puruṣāṇām mātrā sādhimānānām

Now as to the (other) forms of the fire-altar. Twenty-eight man's lengths long (from west to east) and twenty-eight man's lengths across is the body (of the altar), fourteen man's lengths the right, and fourteen the left wing, and fourteen the tail. Fourteen cubits (aratni) he covers (with bricks) on the right, and fourteen on the left wing, and fourteen spans (vitasti) on the tail. Such is the measure of (an altar of) ninety-eight man's lengths with the additional space (for wings and tail).