With accent marks:
Лу́чшее – враг хоро́шего.
The best is the enemy of the good.
The author of the phrase “the best is the enemy of the good” is considered to be the French philosopher and writer of the 18th century Voltaire. He wrote it in his “Philosophical Dictionary” and the novel “Impatient” ("le mieux est I'ennemi du bien"), although such thoughts were expressed by many others including Shakespeare, J. Bruno, and so on.
The interpretation of this phrase varies, but in Russia it is often understood in the sense that in striving for the best, people often spoil the good.
Other Russian proverbs
Put your trust in God, but don't make mistakes yourself
There is no smoke without fire.
Measure seven times, cut one.
All is well that ends well.
In a quiet whirlpool, demons live.
Don't bring your set of rules in a foreign monastery
A well-fed man does not understand a starving one.
We don't appreciate what we have but we cry when we lose it.