Other source:

Finally Kami battles his evil half. He tells Goku that he must vanquish Piccolo because he knows that Goku, knowing that if Piccolo dies Kami must die as well, will not have the heart to kill Piccolo himself. Kami uses the Mafuba technique to seal Piccolo in a Denshi jar, just like what happened centuries earlier. Piccolo counters the attack, sealing Kami in the Denshi jar and swallowing it. Before he is sealed Kami implores Goku to destroy Piccolo at any cost.