With accent marks:
От добра́ добра́ не и́щут.
They do not seek good from good.
Few people know that this is only part of the proverb. Its full version sounds like this: "От овса кони не рыщут, а от добра добра не ищут" (Horses do not roam from oats, but they do not seek good from good). It means that if the horses are fed, they will not run away. If a person is doing well at home, he will not leave the family.
In its shorter version the proverb acquired a second meaning: when doing good to people, one should not expect the same from them. You need to do good selflessly.
Other Russian proverbs
Repetition is the mother of learning.
Another's soul is darkness.
Don't bring your set of rules in a foreign monastery
Start taking care of the dress while it's new, and of your honor while you are young.
The apple never falls far from the tree.
Silent means consent.
What you will sow, that you will reap.
A bad example is contagious.