On his way he has a quarrel with an old man .
On his way he kills him , and for answering a riddle of the Sphinx at the entrance of Thebes gets to marry the queen dowager Jocasta .
On his way he has a quarrel with an old man , and kills him , and for answering a riddle of the Sphinx at the entrance of Thebes gets to marry the queen dowager Jocasta .