Better the foot slip than the tongue.
More French Proverbs:
So long as the wolf is captured the dog will bite his leg.French
Many a one suffers for what he can't help.
French
To rob a robber is not robbing.
French
For some of us happiness comes while we sleep.
French
One often has need of a lesser than oneself.
French
You may as well give a good beating as a bad one.
French