Who is not good for himself is no good for others.
More Yiddish Proverbs:
When you sweep the house, you find everything.
Yiddish
Perfection anywhere is very rare.
Yiddish
The truth is not always what we want to hear.
Yiddish
The truth is not always what we want to hear.
Yiddish
One rotten apple spoils the other.
Yiddish