Why, by making him uncapable of Othello’s place; knocking out his brains.
– William Shakespeare
Othello, Act 4, Scene 2. After Roderigo complains that he has spent all his money and given his jewels to Iago to win Desdemona and found no success, Iago manipulates him further. He convinces Roderigo into believing that he will have a chance with Desdemona if he murders his love rival Cassio. So he sets him up to kill him.