With accent marks:
Не руби́ сук, на кото́ром сиди́шь.
Do not chop the branch you sit on
This proverb is addressed to a person who harms himself by his actions.
The English equivalent of this proverb is "To shoot oneself in the foot".
Other Russian proverbs
Оne can not see the wood for the trees.
One head is good, but two ones are better.
Better to see once than hear a hundred times.
Not everything that glitters is gold.
Bitter truth is better than sweet lies.
Do not dig a hole for another one, you will fall into it yourself.
Without labor, you can not even catch a fish in the pond.
A bad example is contagious.