In one of the more famous Pulp Fiction scenes, Jules and Vincent are eating at a diner when Ringo and Honey Bunny decide to rob it. Their attempt doesn't go well.
At one point, Jules tells Ringo to open up his wallet and take out $1,500.
http://www.youtube.com/watch?v=3PeyiU3uWJ8&t=1m22s
Now, I ain't giving it to him, Vincent. I'm buying something for my money. Wanna know what I'm buying, Ringo?
"What?"
"Your life. I'm giving you that money so I don't have to kill yo' ass."
What does giving Ringo $1,500 have to do with not killing him?