So Lord Ganesha, respecting his mother's want and her command, stood outside the room guarding the room of his mother, mother Parvati. So lot of people came and came to speak to Parvati. Lord Vishnu came, Lord Bhamma came, Rishi Muni came. Ganeshi did not let anybody enter the room. He told everybody to go out. Then Lord Shiva came, not realizing story. Lord Ganesh is the son of him and Parvati