When they grew old, a son was born to them and this son was Mahabhisha. He was called Shantanu, because he was born when his father had controlled his passions by asceticism.
तयोः समभवत् पुत्रो वृद्धयोः स महाभिषः॥ शान्तस्य जज्ञे संतानस्तस्मादासीत् स शान्तनुः।