Shatapatha Brahmana 13.5.4.28

13.5.4.28

athottaraṃ samvatsaramṛtupaśubhiryajate ṣaḍbhirāgneyairvasante ṣaḍbhiraindrairgrīṣme ṣaḍbhiḥ pārjanyairvā mārutairvā varṣāsu ṣaḍbhirmaitrāvaruṇaiḥ śaradi ṣaḍbhiraindrāvaiṣṇavairhemante ṣaḍbhiraindrābārhaspatyaiḥ śiśire ṣaḍṛtavaḥ samvatsaraḥ ṛtuṣveva samvatsare pratitiṣṭhati ṣaṭtriṃśadete paśavo bhavanti ṣaṭtriṃśadakṣarā bṛhatī bṛhatyāmadhi svargo lokaḥ pratiṣṭhitastadvantato bṛhatyaiva candasā svarge loke pratitiṣṭhati

And during the following year he performs the animal sacrifices of the seasons,--six (victims) sacred to Agni in the spring, six to Indra in the summer, six to Parganya, or to the Maruts, in the rainy season, six to Mitra and Varuna in the autumn, six to Indra and Vishnu in the winter, and six to Indra and Brihaspati in the dewy season,--six seasons are a year: in the seasons, in the year, he thus establishes himself. These amount to thirty-six animals,--the Brihatî (metre) consists of thirty-six syllables, and the heavenly world is established upon the Brihatî: and thus he finally establishes himself, by means of the Brihatî metre, in the heavenly world.