Answer:
Jupiter was already being wearied by the Lions frequent complains of how powerful, gigantic and handsome in shape he is. The lion didn't want to accept the fact that he was being a coward and wasn't courageous at that instance.
So in Jupiter's word's he replies "Why do you blame me without a cause?I have given you all the attributes which I possess myself,and your courage never fails you except in this one in-stance."
