Proverbs 25:19 in the World English Bible
Confidence in someone unfaithful in time of trouble is like a bad tooth or a lame foot.
Context
18 A man that beareth false witness against his neighbour is a maul, and a sword, and a sharp arrow.
19 Confidence in an unfaithful man in time of trouble is like a broken tooth, and a foot out of joint.
20 As he that taketh away a garment in cold weather, and as vinegar upon nitre, so is he that singeth songs to an heavy heart.