Genesis 50:17

So shall ye say unto Joseph, Forgive, I pray thee now, the trespass of thy brethren and their sin, for they did unto thee evil. So the sons' fear of Joseph's revenge had caused them to make a full confession to their father and to ask his advice in this difficult matter. Their repentance, their conversion, was now an accomplished fact: they had made a full and free confession. And now, we pray thee, forgive the trespass of the servants of the God of thy father. Thus the brothers received perfect assurance of the forgiveness of their sin, for it is by confessing and forsaking sins that mercy is obtained. And Joseph wept when they spake unto him, it grieved him to think that they believed him capable of such meanness, but he wept also tears of joy over this evidence of complete repentance.