One rotten apple spoils the other.
More Yiddish Proverbs:
With a child in the house, all corners all full.Yiddish
The sun shines brighter after a shower.
Yiddish
Rich man down and poor man up -- they are still not even.
Yiddish
In time, even a bear can be taught to dance.
Yiddish
In time, even a bear can be taught to dance.
Yiddish
Even in heaven, it is not good to be alone.
Yiddish