By Swami Harshananda
Pratardana, the king of Kāśī, was the son of Divodāsa and Mādhavī. His story appears first in the Kausitaki Brāhmanopanisad (3.1-8) of the Rgveda.
By the dint of his prowess and heroism, he goes to the world of Indra who asks him to choose any boon. Though Pratardana refuses to ask any, Indra— identified here with Supreme Brahman— teaches him about his own greatness and asks him to meditate on himself (i. e., Indra) as prāṇa (life-force) and prajñātman (the Intelligent Self).
The entire section is known as Pratardanavidyā or Prānavidyā.
The story as given in the Mahā-bhārata (Anuśāsanaparva 30) states that the king Pratardana whose race had almost been exterminated by the Haihaya king Vitahavya and his sons, went in pursuit of the fleeing Vitahavya. The latter was given shelter by the sage Bhṛgu who protected him. Hence Pratardana had to return to his kingdom without destroying his enemy.
However, by the grace of the sage Bhrgu, Vitahavya became a brāhmaṇa of highly sāttvik nature; and, Pratardana gave up his enmity.
- The Concise Encyclopedia of Hinduism, Swami Harshananda, Ram Krishna Math, Bangalore