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
What you will sow, that you will reap.
~ Seven babysitters make the kid to lose an eye.
You can't help grief with tears.
Not everything that glitters is gold.
Free cheese is only in a mousetrap.
Everything has its time.
If I knew where I would fall, I would lay some straw there.
Where there is no fish even a crayfish is a fish.