Chandogya Upanishad 3.18

mano brahmety upāsīta ity adhyātmam athādhidaivatam ākāśo brahma ity ubhayam ādiṣṭaṃ bhavaty adhyātmaṃ cādhidaivataṃ ca

Let a man meditate on mind as Brahman (n.), this is said with reference to the body. Let a man meditate on the ether as Brahman (n.), this is said with reference to the Devas. Thus both the meditation which has reference to the body, and the meditation which has reference to the Devas, has been taught.

tad etac catuṣpād brahma vāk pādaḥ prāṇaḥ pādaś cakṣuḥ pādaḥ śrotraṃ pādaḥ ity adhyātmam athādhidaivatam agniḥ pādo vāyuḥ pāda ādityaḥ pādo diśaḥ pādaḥ ity ubhayam evādiṣṭaṃ bhavaty adhyātmaṃ cādhidaivataṃ ca

That Brahman (mind) has four feet (quarters). Speech is one foot, breath is one foot, the eye is one foot, the ear is one foot—so much with reference to the body. Then with reference to the gods, Agni (fire) is one foot, Vâyu (air) is one foot, Âditya (sun) is one foot, the quarters are one foot. Thus both the worship which has reference to the body, and the worship which has reference to the Devas, has been taught.

vāg eva brahmaṇaś caturthaḥ pādaḥ so 'gninā jyotiṣā bhāti ca tapati ca bhāti ca tapati ca kīrtyā yaśasā brahmavarcasena ya evaṃ veda

Speech is indeed the fourth foot of Brahman. That foot shines with Agni (fire) as its light, and warms. He who knows this, shines and warms through his celebrity, fame, and glory of countenance.

prāṇa eva brahmaṇaś caturthaḥ pādaḥ sa vāyunā jyotiṣā bhāti ca tapati ca bhāti ca tapati ca kīrtyā yaśasā brahmavarcasena ya evaṃ veda

Breath is indeed the fourth foot of Brahman. That foot shines with Vâyu (air) as its light, and warms. He who knows this, shines and warms through his celebrity, fame, and glory of countenance.

cakṣur eva brahmaṇaś caturthaḥ pādaḥ sa ādityena jyotiṣā bhāti ca tapati ca bhāti ca tapati ca kīrtyā yaśasā brahmavarcasena ya evaṃ veda

The eye is indeed the fourth foot of Brahman. That foot shines with Âditya (sun) as its light, and warms. He who knows this, shines and warms through his celebrity, fame, and glory of countenance.

śrotram eva brahmaṇaś caturthaḥ pādaḥ sa digbhir jyotiṣā bhāti ca tapati ca bhāti ca tapati ca kīrtyā yaśasā brahmavarcasena ya evaṃ veda ya evaṃ veda

The ear is indeed the fourth foot of Brahman. That foot shines with the quarters as its light, and warms. He who knows this, shines and warms through his celebrity, fame, and glory of countenance.