Śatapatha Brāhmaṇa ("of a hundred paths") 4.2.5.9

4.2.5.9

atha yadatra bahiṣpavamānena stuvate | atra ha vā asāvagra āditya āsa tamṛtavaḥ parigṛhyaivāta ūrdhvāḥ svargaṃ lokamupodakrāmantsa eṣa ṛtuṣu pratiṣṭhitastapati tatho evaitadṛtvijo yajamānam parigṛhyaivāta ūrdhvāḥ svargaṃ lokamupotkrāmanti tasmādatra bahiṣpavamānena stuvate

And as to why they chant the Bahishpavamâna here (near the kâtvâla). In the beginning, forsooth, yonder sun was here on earth. The seasons embraced him and ascended from hence to the heavenly world: there he burns firmly established in the seasons. And in like manner do the priests thereby embrace the sacrificer and ascend from hence to the heavenly world: this is why they chant the Bahishpavamâna h ere.