Don't judge a book by it's cover. Saying in Spanish?

Hi everyone~!

I was just wondering if there was a saying in Spanish that means something like "looks can be deceiving" or "don't judge a book by it's cover"

Also, I was wondering if there is any quote that involves something about how important friendship is?


Thank you so much~! ^___^

 

No se debe juzgar un libro por sus tapas or las apariencias engañan

Sobre la amistad http://es.wikiquote.org/wiki/Amistad