With accent marks:
Ка́шу ма́слом не испо́ртишь.
You can't spoil the porridge with butter.
From time immemorial, porridge was loved and respected in Russia. It was cooked from wheat, buckwheat, oats, etc. To make it tastier, people added more butter.
This Russian proverb is used to say that something good can not be bad even in large quantities.
Other Russian proverbs
Start taking care of the dress while it's new, and of your honor while you are young.
Bitter truth is better than sweet lies.
You see your friends in the times of trouble.
Being a guest is good, but being at home is better.
Strike the iron while it's hot.
Put your trust in God, but don't make mistakes yourself
The demon is not as scary as he is depicted.
In a healthy body, healthy mind.