Whoever rebukes a person will in the end gain favor rather than one who has a flattering tongue. (Proverbs 28:23 NIV)
The one who reproves another will in the end find more favor than the one who flatters with the tongue. (Proverbs 28:23 NET)
Basically, the verse (which has different translations for this post), directly tells us that it is much more good and favorable if we straightforwardly tell a person of the things that he/she should not be doing, rather than saying that those “unwanted” things can come to pass and that this person may one day realize that there is something wrong.
Simply put, if we are friends with that person, we will tell his/her wrongdoings. We should not let our friends venture the depths of sin, instead, while it is still in the stages of prematurity, we should hold his/her hand and say that there is a problem. You just have to say the words with sense of care and love, expressing that you do not want your friend to turn to the wrong way, and that you are so much willing to accompany him/her to righteousness.
Be the friend your friends need. For blessed is the person who guides his/her friends, and not letting them to fall in madness.