Śatapatha Brāhmaṇa ("of a hundred paths") 14.2.1.16

14.2.1.16

atha śaphāvādatte gāyatraṃ cando'si traiṣṭubhaṃ cando'sīti gāyatreṇa caivaināvetattraiṣṭubhena ca candasādatte dyāvāpṛthivībhyāṃ tvā parigṛhṇāmītīme vai dyāvāpṛthivī parīśāsāvādityaḥ pravargyo'muṃ tadādityamābhyāṃ dyāvāpṛthivībhyām parigṛhṇātyatha mauñjena vedenopamārṣṭyasāveva bandhuḥ

He then takes the two lifting-sticks, with (Vâg. S. XXXVIII, 6), 'The Gâyatrî metre thou art,--the Trishtubh metre thou art,'--he thus takes them with both the Gâyatrî and the Trishtubh metres;--'with heaven and earth I encompass thee,'--for the two lifting-sticks are indeed these two, heaven and earth; and the Pravargya is the sun: he thus encompasses yonder sun within these two, heaven and earth. Thereupon (having lifted up the pot) he sweeps it clean with a branch of reed grass: the mystic import of this is the same as before.