What does "なるなって" mean?


I've been trying to understand what is being said below. In particular, the
usage of 「なるなって」.
[![](https://i.stack.imgur.com/0Pb2f.png)](https://i.stack.imgur.com/0Pb2f.png)

My translation currently stands as:

そうだよ。言葉に責任持たなきゃね

"That's right. You must hold responsibility for your words, right?"

約束を守れないような人間にはなるなって教えてくれたのはミトさんだよ

"Mito-san is teaching me to become so that humans are not to be trusted (lit.
not-able-to-hold-a-promise-seeming)"

I can't understand how 「なるなって」 is used in the sentence above. At face value
I'm taking it to mean 'becoming to become'. For example, 医者になるなって would mean
"I'm only just finally reaching this long-awaited goal of being a doctor"
(lit. I'm becoming to become a doctor).

Can anyone shed some light on how 「なるなって」 is used?




This is the [negative imperative
な](https://japanese.stackexchange.com/questions/47246/%e5%8b%95%e8%a9%9e%e8%be%9e%e6%9b%b8%e5%bd%a2%ef%bc%8b%e3%81%aa-%e3%81%af%e3%81%a9%e3%81%86%e3%81%84%e3%81%86%e6%84%8f%e5%91%b3%e3%81%a7%e3%81%99%e3%81%8b),
plus the quotative って. So we have:

> 約束を守れないような人間にはなるなって教えてくれたのはミトさんだよ！  
>  The one who taught me "Don't become someone who can't keep their promises"
> — that's Mito!




This is the [negative imperative
な](https://japanese.stackexchange.com/questions/47246/%e5%8b%95%e8%a9%9e%e8%be%9e%e6%9b%b8%e5%bd%a2%ef%bc%8b%e3%81%aa-%e3%81%af%e3%81%a9%e3%81%86%e3%81%84%e3%81%86%e6%84%8f%e5%91%b3%e3%81%a7%e3%81%99%e3%81%8b),
plus the quotative って. So we have:

> 約束を守れないような人間にはなるなって教えてくれたのはミトさんだよ！  
>  The one who taught me "Don't become someone who can't keep their promises"
> — that's Mito!

