Matsya Purana 48.87

48.87

satputreṇa tu dharmajña kṛtārtho 'haṃ yaśasvinā
muktvātmānaṃ tato 'sau vai prāptavānbrahmaṇaḥ kṣayam //

That sage was instantly restored to his vision after being smelled by Surabhi, and got a long lease of life, along with beautiful eyes and form. He came to be known as Gautama, on account of his being relieved of his blindness by (the smelling of) the cow. Afterwards, Kâkṣîvâna, the son of that Śudra nurse, went with his father, Dîrghatamâ, to Girivraja, and after seeing and touching him practised penances for a long time, and in the fulness of time, through his asceticism, he purified the body obtained from a Śudra mother and became a Brâhmaṇa, at which his father told him : “I consider myself to-day blessed with a son through you, and O pious one ! I feel blessed on getting a righteous and renowned son like you, who after casting off his previous sheath, has became a Brâhmaṇa.”—84-87.