Pañcaviṃśa (Tāṇḍya Mahā) Brāhmaṇa 10.12.9

10.12.9

ṣaḍ ahāni vibhajanti ṣaḍ ṛtava ṛtūnāṃ dhṛtyā ṛtūnāṃ pratiṣṭhityā atho ṛtūnām eva tad rūpaṃ kriyate ṣaḍ u puruṣā yān agnir anuvihriyate

They divide [it across] six days; there are six seasons, for the upholding of the seasons, for the firm standing of the seasons; thus its form is made that of the seasons; and there are six persons according to whom Agni is distributed.