Śatapatha Brāhmaṇa ("of a hundred paths") 4.1.2.23

4.1.2.23

atha nīcā pāṇinā | madhyame paridhau pratyagupamārṣṭīdaṃ vā upāṃśu hutvottānena pāṇinā madhyame paridhau prāgupamārṣṭyathātra nīcā pāṇinā madhyame paridhau pratyagupamārṣṭi pratyañcamevāsminnetadudānaṃ dadhāti devebhyastvā marīcipebhya iti so 'sāveva bandhuḥ

He then rubs (the wiped-off Soma) upon the middle enclosing stick from east to west with the palm of his hand turned downwards. For even now, after offering the Upâmsu, he rubbed it upon the middle enclosing stick from west to east with the palm of his hand turned upwards; but here he does so from east to west with the palm of his hand turned downwards--whereby he puts the in-breathing into him as one tending towards him--with, 'Thee for the gods sipping motes of light!' The significance is the same as before.