The mice will never play with the kittens.
More Spanish Proverbs:
To lather an ass's head is only wasting soap.Spanish
If it is good then the deed is more important than the intention; if it's bad then the intention is worse than the deed.
Spanish
If three people say you are an ass, put on a bridle.
Spanish
Don't bite off more than you can chew.
Spanish
There would be no ill word if it were not ill taken.
Spanish
It is a bad hen that eats at your house and lays at another's.
Spanish