Chandogya Upanishad 4.5.2

4.5.2

brahmaṇaś ca te pādaṃ bravāṇi iti \
bravītu me bhagavān iti \
tasmai ha uvāca \
prācī dik kalā \
praticī dik kalā \
dakṣiṇā dik kalā \
udīcī dik kalā \
eṣa vai somya catuṣkalaḥ pādo brahmaṇaḥ prakāśavān nāma \\405.2\

then the bull spoke to him, saying: ‘Satyakāma!’ ‘Sir!’ he replied. ‘We have reached a thousand, my dear. Bring us to the teacher’s house. And let me tell you a quarter of Brahma.’ ‘Tell me, Sir.’ To him it then said: ‘One sixteenth is the east. One sixteenth is the west. One sixteenth is the south. One sixteenth is the north. This, verily, my dear, is the quarter of Brahma, consisting of four sixteenths, named the Shining.