Shatapatha Brahmana 4.5.9.6

4.5.9.6

atha saptame 'hanvyūhati | grahānvyūhanti candāṃsi tacukrāgrān gṛhṇāti bārhataṃ vā etatsaptamamaharbhavatyeṣa vai śukro ya eṣa tapatyeṣa u eva bṛhaṃstasmācukrāgrān gṛhṇāti

Then, on the seventh day, he transposes the grahas, and they transpose the metres. There he draws the cups beginning with the Sukra cup; for that seventh day belongs to the Brihatî ('great' metre); for the Sukra is he that burns yonder, and he indeed is great: therefore he draws the cups beginning with the Sukra.