Śatapatha Brāhmaṇa ("of a hundred paths") 10.2.6.3

10.2.6.3

sa digbhireva saptavidhaḥ ye prācyāṃ diśi raśmayaḥ saikā vidhā ye dakṣiṇāyāṃ saikā ye pratīcyāṃ saikā ya udīcyāṃ saikā ya ūrdhvāyāṃ saikā ye'vācyāṃ saikā maṇḍalameva saptamī vidhā

By the regions it is sevenfold,--the rays which are in the eastern region are one part, and those in the southern are one, and those in the western are one, and those in the northern are one, and those in the upper (region) are one, and those in the lower (region) are one, and the disk itself is the seventh part.