Chapter 26 - Atticus is reelected to the state legislature that year
Chapter 26 - Atticus helps Scout try to figure out why Jem is acting out badly, and says it's because Jem is holding anger in and he will let it out eventually.
The thing that makes this phrase so powerful is how affirmative he is. He isn't asking a question like "Could you please let me eat in this room?" He is threatening the people not allowing him to eat there. He is threatening their job.