Took birth control almost 4 hours late?

I usually take it at 9 and my phone alarm didn't go off for some reason because it just does that sometimes and I forgot, usually I don't worry if it's within about 2 hours but I just took it a few minutes ago... Would i still be safe tomorrow? Even if a condom is not used I use the withdrawal method (which I wouldn't do without birth control!) but since I was almost 4 hours late would it still be safe? I would assume so, but I would like some input. Thank you.