Śatapatha Brāhmaṇa ("of a hundred paths") 6.4.2.9

6.4.2.9

saṃsīdasva mahāṃ asīti | idamevaitadretaḥ siktaṃ saṃsādayati tasmādyonau retaḥ siktaṃ saṃsīdati śocasva devavītama iti dīpyasva devavītama ityetadvi dhūmamagne aruṣam miyedhya sṛja praśasta darśatamiti yadā vā eṣa samidhyate 'thaiṣa dhūmamaruṣaṃ visṛjate darśatamiti dadṛśa iva hyeṣaḥ

[Vâg. S. XI, 37; Rik S. I, 36, 9] 'Seat thee, thou art great,'--he now causes the infused seed to establish itself, whence the seed infused into the womb establishes itself;--'burn thou, best gladdener of the gods!'--that is, 'shine thou, best gladdener of the gods; send forth, O Agni, worthy partaker of the offering, thy showy, ruddy smoke!' for when he (Agni) is kindled, he sends forth his ruddy smoke,--the showy, for it, as it were, shows itself.