Shatapatha Brahmana 10.5.1.5

10.5.1.5

sā vā eṣā vāktredhāvihitā ṛco yajūṃṣi sāmāni maṇḍalamevarco'rciḥ sāmāni puruṣo yajūṃṣyathaitadamṛtaṃ yadetadarcirdīpyata idaṃ tatpuṣkaraparṇaṃ tadyatpuṣkaraparṇamupadhāyāgniṃ cinotyetasminnevaitadamṛta ṛṅmayaṃ yajurmayaṃ sāmamayamātmānaṃ saṃskurute so'mṛto bhavati

This speech, indeed, is threefold--the Rik-verses, the Yagus-formulas, and the Sâman-tunes the Rik-verses are the orb, the Sâman-tunes the light, and the Yagus-formulas the man (in the sun); and that immortal element, the shining light, is this lotus-leaf: thus, when he builds up the Fire-altar after laying down the lotus-leaf, it is on that immortal element that he builds for himself a body consisting of the Rik, the Yagus, and the Sâman; and he becomes immortal.