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
It is not a place that makes a person look good, but a person that makes a place look good.
(lit.) Whoever gets up early, God gives him
With whom you are friends with, from them you will learn.
The apple never falls far from the tree.
Don't bring your set of rules in a foreign monastery
Free cheese is only in a mousetrap.
The further into the forest, the more firewood is there.
Water does not flow under a lying stone.