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
With whom you are friends with, from them you will learn.
Live for a century, learn for a century, but die being a fool anyway.
We don't appreciate what we have but we cry when we lose it.
All is well that ends well.
Where there is no fish even a crayfish is a fish.
Do not look at a given horse's teeth.
Silent means consent.
What you will sow, that you will reap.