عَنْ أَبِي رُقَيَّةَ تَمِيمِ بْنِ أَوْسٍ الدَّارِيِّ رَضِيَ اللهُ عَنْهُ أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ: “الدِّينُ النَّصِيحَةُ.” قُلْنَا: لِمَنْ؟ قَالَ: “لِلَّهِ، وَلِكِتَابِهِ، وَلِرَسُولِهِ، وَلِأَئِمَّةِ الْمُسْلِمِينَ وَعَامَّتِهِمْ.”
On the authority of Abi Ruqayyah Tameem ibn Aws ad-Dariyy (ra) that the Prophet salAllahu ‘alayhi wa sallam said, “The religion is naseehah (good advice).” The people asked, “To whom?” The Prophet salAllahu ‘alayhi wa sallam replied, “To Allah and to His book and to His Messenger and to the leaders of the Muslims and to the common folk of Muslims.” [ Muslim]
The linguistic meaning of Naseehah is ‘to purify or to gather that which is dispersed.’ Naseehah means wanting good for someone with a sincere heart which is free from any defect/deficiencies and wanting all good for that particular person.
Naseehaha about Allah subhanahu wa ta’ala involves: purifying our hearts for Allah subhanahu wa ta’ala; striving hard in worship and doing it according to the Sunnah; cleansing our minds and thoughts from deviant ideologies; being sincere in our worship. We love for His sake and hate for His sake; glorifying Allah subhanahu wa ta’ala and His laws and recognizing His blessings over us.
Nasheeha about Allah’s Books involves: believing in the entire Qur’an and acting upon them; having immense love and devotion for it; adorning ourselves with the manners it teaches us; being pure when holding it; and ensuring we read our daily portion of the Qur’an.
Naseehah about the Prophet salAllahu ‘alayhi wa sallam involves: believing in him; putting his statement above any other human’s; having eagerness to know more about him; studying his Seerah the way one studies the Qur’an; following his Sunnah; trying to learn more about his manners and emulating them; and loving what he loved and hating what he hated.
Naseehah about the Muslim leaders involves: wanting good for them; asking Allah subhanahu wa ta’ala to guide them to the truth; making du’a for them and wanting the Ummah to be united under them; advising them personally and not publicly; remembering the statement: Rulers are like their followers (so first reform yourself); having love and respect for the scholars and not searching for their mistakes.
Naseehah to the common folk of the Muslims involves: loving for them what we love for ourselves and hating for them what we hate for ourselves; respecting their elders and showing mercy to their youngsters; being happy when they are happy and sad when they are sad; carrying no envy for them in our hearts (qalb saleem – a sound heart); and wishing good for them.
Slightly modified from this source.