Mahabharata 3.139.22

3.139.22

anena tu gurūnduḥkhāttoṣayitvā svakarmaṇā |
kālena mahatā kleśādbrahmādhigatamuttamam || 22 ||

"Lomasa said, 'The celestials, O king, were well pleased with Arvavasu for his acts. And they made him engaged as the chief priest in the sacrifice (of Vrihadyumna), and Paravasu to be dismissed from it. Then Agni and the other celestials (of their own accord) bestowed boons on Arvavasu. And they also prayed that his father might be restored to life. He further prayed that his brother might be absolved from his sin; that his father might have no recollection of his having been slain; that Bharadwaja and Yavakri might both be restored to life; and that the solar revelation might attain celebrity (on earth). Then the god said, 'So be it,' and conferred on him other boons also. Thereat, O Yudhishthira, all of these persons regained their life. Yavakri now addressed Agni and the other deities, saying, 'I had obtained a knowledge of all the Vedas, and also practised penances. How came it then, O chiefs of the immortals, that Raivya succeeded in killing me in that way?' Thereupon the gods said, 'O Yavakri, never act again as those have done. What thou askest about is quite possible, for thou hast learnt the Vedas without exertion, and without the help of a preceptor. But this man (Raivya) bearing various troubles, had satisfied his preceptor by his conduct, and obtained (from the latter) the excellent Vedas through great exertions and in a long time.'