I resigned./I quitted my job./I've put in my notice.
The airline has downsized its workforce by 30%.
A: Emily, could you spare a few minutes?
B: Sure. What do you need?
A: Well, I wanted to let you know that I've put in my notice.
B: Really? Why?
A: It's complicated. But basically it boils down to one thing. This company is downsizing and I can't continue working for a company that may let me go.
B: But surely they wouldn't fire you! You are one of the most experienced managers here.
A: Well, to be honest, there's another reason. I've got a better offer.
B: Well, that's great news. Congratulations. Where will you be located?
A: The head office is in New York, but I'll be dealing with overseas companies and flying to this side of the world from time to time.
B: It'll be sad to see you go, but it sounds like you've found yourself a great opportunity.
A: I have. I feel lucky. I look forward to dealing with overseas companies and at the same time having a chance to use English more.
B: I'm sorry to bring this up now, but would it be possible for you to write me a letter of recommendation before you go?
A: Of course I can. In fact, if there are any other job opportunities at this new company. I'll recommend you personally.
B: Thanks. I appreciate that.