LEV600 [Among the fundamentals of repentance]: Turning as many as possible away from transgression, as it is written (Yechezkel 18:30): "Return and turn others from all your offenses." We are hereby taught that this is one of the principles of repentance. And it is written [this verse]: "You shall surely rebuke your fellow man, and not bear sin because of him." This teaches us that if one does not reprove the other he is punished for his sins. And David said, likewise (Tehillim 51:15): "I will teach offenders Your ways and sinners will return to You."