I actually knew this. Though i thought it was only Vegeta's "I'll beat you".
When you think about it, the ending was pretty lame. Goku kidnaps a 9 year old kid to leave his family and friends behind and take the rest of his life to train this kid to be earth's defender, although it's all a lie and he's doing that because he wants to fight. Oh and Vegeta going back on his "You're #1". Is this shit Super or what?