Śatapatha Brāhmaṇa ("of a hundred paths") 3.5.3.22

3.5.3.22

atha pratiprasthātā | uttaraṃ havirdhānamupastabhnāti divo vā viṣṇa uta vā pṛthivyā maho vā viṣṇa urorantarikṣāta ubhā hi hastā vasunā pṛṇasvā prayaca dakṣiṇādota savyādviṣṇave tveti methīmupanihantītaratastato yadu ca mānuṣe tadyadvaiṣṇavairyajurbhirupacaranti vaiṣṇavaṃ hi havirdhānam

The assistant then props the northern cart, with (Vâg. S. V, 19), 'Either from the heaven, O Vishnu, or from the earth, or from the great, wide airy region, O Vishnu, fill both thine hands with wealth and bestow on us from the right and the left! For Vishnu thee!' He fixes the prop in a different place from where (it is fixed) in ordinary practice. The reason why he performs with prayers to Vishnu is that the Soma-cart belongs to Vishnu.