I always used to think that nasihah literally meant to give advice because that’s how many of us use the term. Apparently, I was wrong:

Abu Raqiyyah Tamin bin Aws ad-Dari radi Allahu `anhu, may Allah subhanahu wa ta`ala be pleased with him, narrated that the Prophet s.a.w. said: “[Islam] is an-nasihah.” We said, “To whom?” He said, “To Allah, to His book, to His messenger, the leaders of the Muslims and to the general populous of the Muslims” (Muslim).

Upon reading this hadith (saying of the Prophet s.a.w.) it became clear that nasihah does not mean advice. How could one possibly advise God or His book? Nasihah actually means sincerity; it is striving to seek the best outcome in any situation in life. So when we have nasihah with Allah azza wa jal, that means that we are sincere in worshipping Him and following His commandments.

Nasihah is not so much about advice; rather it is about seeking the good and benefit in a situation. If we keep this in mind, we realize that when we give nasihah to our leaders and fellow Muslims it is not to prove our point, or because we feel violated; we don’t do it in anger or haste, but rather humbly, honestly and strategically. We look to improve the situation, or the individual, instead of debasing and humiliating them. Thus, we give nasihah in the best way possible: the way that it will be received.

This, in essence, is one of the very reasons we come together as a community. We seek to uplift each other in times of hardship and grow together in times of ease. It allows us to multiply our potential and seek the best in any situation. So don’t leave a brother (or sister) hanging and please keep the nasihah coming.

Source:
http://www.suhaibwebb.com/relationships/brotherhood-sisterhood/understanding-nasihah/