Chandogya Upanishad 4.5

atha hainam ṛṣabho 'bhyuvāda satyakāma 3 iti bhagava iti ha pratiśuśrāva prāptāḥ somya sahasraṃ smaḥ prāpaya na ācāryakulam

The bull of the herd (meant for Vâyu) said to him: 'Satyakâma!' He replied: 'Sir!' The bull said: 'We have become a thousand, lead us to the house of the teacher;

brahmaṇaś ca te pādaṃ bravāṇi iti bravītu me bhagavān iti tasmai hovāca prācī dik kalā pratīcī dik kalā dakṣiṇā dik kalā udīcī dik kalā eṣa vai somya catuṣkalaḥ pādo brahmaṇaḥ prakāśavān nāma

'And I will declare to you one foot of Brahman.' 'Declare it, Sir,' he replied. He said to him; 'The eastern region is one quarter, the western region is one quarter, the southern region is one quarter, the northern region is one quarter. This is a foot of Brahman, consisting of the four quarters, and called Prakâsavat (endowed with splendour).'

sa ya etam evaṃ vidvāṃś catuṣkalaṃ pādaṃ brahmaṇaḥ prakāśavān ity upāste prakāśavān asmiṃl loke bhavati prakāśavato ha lokāñ jayati ya etam evaṃ vidvāṃś catuṣkalaṃ pādaṃ brahmaṇaḥ prakāśavān ity upāste

'He who knows this and meditates on the foot of Brahman, consisting of four quarters, by the name of Prakâsavat, becomes endowed with splendour in this world. He conquers the resplendent worlds, whoever knows this and meditates on the foot of Brahman, consisting of the four quarters, by the name of Prakâsavat.