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
Poor people are inventive.
You see your friends in the times of trouble.
Crowded, but not aggrieved.
In a quiet whirlpool, demons live.
A bad example is contagious.
We don't appreciate what we have but we cry when we lose it.
Оne sees the mote in another's eye and ignores the log in his own.
The demon is not as scary as he is depicted.