Sorry! I forgot about NE when we were still talking about imperative mood.

Expressing the fact that something is prohibited goes like this:

Ne = Don’t

2nd PS: Don’t say that. – Ne mondd ezt!

3rd PS: He’d better not say that. – Ne mondja ezt!

1nd PP: We shouldn’t say that. – Ne mondjuk ezt!

2nd PP: Don’t say that. – Ne mondjátok ezt!

3rd PP: They’d better not say that. – Ne mondják ezt!

And the 1st PS can go like this:

Most csináljam vagy ne csináljam?
Now I should do it or I shouldn’t do it?

Ne menjek veled?
Don’t you want me to go with you?

It’s always NE!

You use NE even if you use the adverb SOHA = NEVER!!! Double negation is a must in Hungarian.

Never say that again. – Soha többet ne mondd ezt!