Mahabharata 13.30.2

13.30.2

suduṣkaraṃ vahanyogaṃ kṛśo dhamanisaṃtataḥ |
tvagasthibhūto dharmātmā sa papāteti naḥ śrutam || 2 ||

'Sakra said, 'One born on a Chandala cannot, by any means acquire the status of a Brahmana. Do thou, therefore name some boon so that all this labour of thine may not prove fruitless--Thus addressed by the chief of the celestials, Matanga became filled with grief. He repaired to Prayaga, and passed there a hundred years, standing all the while on his toes. In consequence of the observance of such Yoga which was extremely difficult to bear, he became very much emaciated and his arteries and veins became swollen and visible. He was reduced to only skin and bones. Indeed, it has been heard by us that the righteous-souled Matanga, while practising those austerities at Gaya, dropped down on the ground from sheer exhaustion. The lord and giver of boons, engaged in the good of all creatures, viz., Vasava beholding him falling down, quickly came to that spot and held him fast.'