I believe this was asked once before. Not sure though.
Anyway, some might think this is a spoiler, so you might want to add that next time.
Highlight from this point on:
To finish this quest is simple yet it's not. First choose the insults as told in the walkthrough here on this site. Then if he still wont attack, close the talk window and open it up again. Then choose to taunt him. After he says goodbye or what ever let him wail on you until ur about halfway dead. Then he'll say things about the race and what not. then go to his mother and talk to her and that should finish the quest.
Hope that helped.
