You said it/You said it yourself

[Ashraful Haque]

I looked up 'you said it'. It is said when you agree with someone.
"How stupid of me to lend him that money!" "You said it!"

In a video game a character says to another character 'you said it yourself.'
A: I don't know this place.
B: You said it yourself that you came here before.

If the sentence is correct, my questions are:
1. Why not simply say "you said you came here before"?
2. Is the 'it' necessary? (You said yourself)

 

[Skrej]

'You said it yourself' is pointing out that that the speaker has made already made the very point you're making, whereas 'you said it' is more for noting that the speaker is the one suggesting it, not you. In such cases, it's often followed by "not me." It can be used for agreement as well.

How stupid of me to lend him that money!
You said it (not me)! (You're the only suggesting you're stupid, not me.)

It's 5:00 on a Friday. Let's stop working and go grab a beer.
You said it! (I agree this is a good idea.)

In a video game a character says to another character 'you said it yourself.'
A: I don't know this place.
B: You said it yourself that you came here before.

If the sentence is correct, my questions are: Yes, it's correct.
1. Why not simply say "you said you came here before"? It's just a way of reminding them they've previously stated that they've been there before. Your version is also acceptable, but it doesn't stress the fact as much.
2. Is the 'it' necessary? (You said yourself) No, 'it' is simply an intensifier here, and could be omitted.

 

[Tarheel]

I think this would be more natural. (See below )

A: I don't know this place.
B: What do you mean? You said you've been here before.

Having said that, "You said it yourself!" makes perfect sense in the right context.