If you encounter your enemy's ox or donkey wandering astray, you must return it to him (Exodus 23:4).
In this mitzvah, the Torah makes two demands: (1) to go out of our way to return a lost animal to its rightful owner, and (2) to overcome our hostile feelings towards our enemy if the lost animal is his.
If this is what is demanded toward a mere belonging of an enemy, how much more are we responsible when we see friends going astray and acting improperly? Yet, how often do we avoid telling them that we feel what they are doing is wrong? We rationalize by saying: "We do not wish to interfere in their private affairs. How they run their life is their own business," or "We don't want to offend them." A popular billboard declares: "A true friend does not allow a friend to drive drunk." If you truly care for others, you will take the necessary steps to protect them from themselves, even if they may be angry at you for doing so. Honesty is more potent than sympathy. A person who has suffered from grievous mistakes often says: "If only someone had stopped me!" Drunk driving is not the only destructive behavior which a true friend would try to stop. Whenever we see that a friend is doing something which we sincerely believe to be wrong, we have a responsibility to convey our opinion to him or her. Failure to do so comes from either of two rationalizations: (1) I am not really his or her friend, or (2) I really do not believe the behavior is wrong. In either case, we are guilty of insincerity.