On the authority of Tameem Ad-Daaree (radhiyallaahu ‘anhu) who said that the Messenger of Allaah (sallallaahu ‘alayhi wa sallaam) said, “The religion is sincerity, the religion is sincerity, the religion is sincerity.” They said, “To who O Messenger of Allaah?” He said, “To Allaah, and His Book, and His Messenger, and the Imaams (leaders) of the Muslims, and their common folk.” (Reported by Muslim)
The Prophet (sallallaahu ‘alayhi wa sallaam) repeated this word (Naseehah – sincerity) showing the importance of the status (of it), and giving guidance to the Ummah (Muslim nation) that they should know with true knowledge that religion, all of it – its apparent aspects and its internal aspects – is contained in sincerity. And it (sincerity) is the complete establishment of these five rights.
So sincerity to Allaah is acknowledging the oneness of Allaah, and His uniqueness in His perfect attributes in a manner that no one shares with Him in them in any way whatsoever. It is also the establishment of His worship, both outwardly (with the actions) and inwardly (with the heart). And it is to turn to Him in every time with worship and servitude, and asking Him with hope and fear, along with repenting to Him and constantly asking His forgiveness. This is because the slave of Allaah will definitely have something of shortcomings regarding the obligations of Allaah, or commission of some of the forbidden things. Thus, with continuous repentance and constant seeking of forgiveness, the person’s deficiency is made up for, and his actions and speech are perfected.
In reference to sincerity to Allaah’s Book, then that is by memorizing it, and contemplating it, and learning its words and meanings, and striving to act according to it within oneself and with others.
In reference to sincerity to the Messenger, then it is by believing in him, loving him, and placing him in regards to love, before oneself, wealth and children. And it is following him in the fundamentals of the religion and its branches. And it is giving precedence to his speech over the speech of everyone else. It is also striving to follow his guidance and aiding his religion.
In reference to sincerity to the Imaams (leaders) of the Muslims – and they are their authority figures, such as the Great Imaam (the Khaleefah), as well as the rulers (Umaraa’), and the judges, and all of those who have some form of authority, whether it be general or specific. Sincerity to them is in believing in their authority, and listening to them and obeying them, and encouraging the people to do so. It is also doing whatever one is able to do to give them proper direction (guidance) and alerting them to everything that would benefit them and benefit the people, and assist them to establish their obligation.
In reference to sincerity to the common folk of the Muslims, then it is by loving for them what one would love for himself, and hating for them what one would hate for himself, and making effort in that regard according to one’s ability. For verily whoever loves something, he strives for it, and he makes effort in making it a reality and perfecting it.
So the Prophet (sallallaahu ‘alayhi wa sallaam) explained sincerity with these five matters, which comprise the establishment of Allaah’s rights, the rights of His Book, the rights of His Messenger, and the rights of all of the Muslims with their different circumstances and statuses. And that contains the religion in its entirety. And nothing is left except that it is included within this comprehensive and all-inclusive statement. And Allaah knows best.