Upakosala Kāmalāyana lived twelve years with Satyakāma Jābāla as a celibate disciple, studying the scriptures and looking after his teacher’s sacrificial fires. On the completion of that period, other students were permitted to go home. The only exception was Upakosala. He was detained.
Satyakāma’s wife said to him: ‘The brahmacārin is much reduced by austerities and has looked after the fires with great care. Lest the fires blame you, I suggest you teach him.’ But Satyakāma did not teach him. Instead, he left on a journey.
Upakosala was upset and started fasting. His teacher’s wife said to him: ‘Brahmacārin, eat something. Why are you not eating?’ Upakosala said: ‘There are too many desires in me and they are pulling me in different directions. I am like one suffering from many ailments. I don’t want to eat’.
Then the fires—the Dakṣiṇāgni, the Gārhapatya, and the Āhavanīya—began to say to each other: ‘This brahmacārin has become thin from practising austerities. He has so long looked after us with great care. Let us teach him.’ They said to Upakosala, ‘Prāṇa is Brahman, ka (happiness) is Brahman, and kha (space) is Brahman.’
Upakosala said: ‘I know that prāṇa is Brahman. But that ka and kha are Brahman I do not know.’ The fires replied, ‘That which is ka is also kha, and that which is kha is also ka.’ Then the fires taught him that Brahman was both prāṇa and ākāśa (space).