Harry Potter and the Chamber of Secrets
All Harry's spellbooks, his wand, robes, cauldron, and top-of-the-line Nimbus Two Thousand broomstick had been locked in a cupboard under the stairs by Uncle Vernon the instant Harry had come home. What did the Dursleys care if Harry lost his place on the House Quidditch team because he hadn't practiced all summer? What was it to the Dursleys if Harry went back to school without any of his homework done? The Dursleys were what wizards called Muggles (not a drop of magical blood in their veins), and as far as they were concerned, having a wizard in the family was a matter of deepest shame. Uncle Vernon had even padlocked Harry's owl, Hedwig, inside her cage, to stop her from carrying messages to anyone in the Wizarding world. (1.27)
"I'll be in my bedroom, making no noise and pretending I'm not there," said Harry tonelessly. (1.43-44)
[Uncle Vernon] was bearing down on Harry like a great bulldog, all his teeth bared. "Well, I've got news for you, boy... I'm locking you up...You're never going back to that school...never...and if you try and magic yourself out – they'll expel you!"
And laughing like a maniac, he dragged Harry back upstairs.
Uncle Vernon was as bad as his word. The following morning, he paid a man to fit bars on Harry's window. He himself fitted a cat-flap in the bedroom door, so that small amounts of food could be pushed inside three times a day. They let Harry out to use the bathroom morning and evening. Otherwise, he was locked in his room around the clock. (2.110-112)