Garudapurana 1.217.4

1.217.4

oṃ bhūḥ oṃ bhuvaḥ oṃ svaḥ oṃ mahaḥ oṃ janaḥ oṃ tapaḥ oṃ satyaṃ tatstripadā /
oṃ āpo jyo 'tī raso 'mṛtaṃ brahma bhūrbhuvaḥ svarom /
oṃ sūryaścetyādi /
oṃ āpaḥ punantvityādi /
oṃ agniścetyādi //

“Oṃ bhūḥ, oṃ bhuvaḥ, oṃ svaḥ, oṃ mahaḥ, oṃ janaḥ, oṃ tapaḥ, oṃ satyam”—this has three feet. / “Oṃ, waters, light, essence, nectar, Brahman, bhūḥ, bhuvaḥ, svaḥ, om.” / “Oṃ sūryaśca…” and so forth; / “Oṃ āpaḥ punantu…” and so forth; / “Oṃ agniśca…” and so forth.