it's an ill bird that fouls its own nest
An unwise or disreputable person does things that ultimately cause them problems. A: "Oh man, why would he say something insulting like that about the boss's daughter at the holiday party? B: "I don't know—it's an ill bird that fouls its own nest."
It's an ill bird that fouls its own nest.
Prov. Only a foolish or dishonorable person would bring dishonor to his or her self or his or her surroundings.; Only a bad person would ruin the place where he or she lives. (See also foul one's own nest.) I don't like my new neighbor. Not only does he never mow his lawn, he covers it with all kinds of trash. It's an ill bird that fouls its own nest.