Wish Granted of Demon

Mahadev says to Vastram that a child who is undefeatable and will live forever cannot be granted to you as a wish. Demon says Mahadev that he has prayed for years, is this what he will get for his bhakti? Mahadev tells Vastram that he can grant him a wish, his son will be all-powerful as he is born. Mahadev grants Vastram his wish.