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
The eyes are scared, but the hands are doing.
To live a life is not the same (not as easy) as to go through a field.
Do not look at a given horse's teeth.
If you are chasing two hares at once, you won’t catch a single one.
The beauty of a debt is its payment
In a quiet whirlpool, demons live.
Each sandpiper praises its swamp.
A titmouse in hands is better than a crane in the sky.