Why can 言ってんじゃねーぞ be an order?


I've been learning japanese for quite a while and always wondered why :

> 言ってんじゃねえぞ

could be an order. Whereas something like :

> 言わない

can't be an order.

Because basically, 【言ってんじゃねぞ】 is just :

> 言う の テ形
>
> 助動詞 いる not pronounced since it's a contraction
>
> Contraction of the particle の (ん)
>
> And じゃない

So I don't understand why 【○○てんじゃねえぞ】can be understood as :

"Don't ***"

Thanks




Expanding the contraction 言ってんじゃねぇぞ, you get 言っているのではないぞ as you say, which is
a のだ form negated. Now, a のだ form can be used as a virtual order and its
negative form can be prohibition.

