Tamim ad-Dari radhiallahu 'anhu said, "The Prophet sallallahu 'alayhi wa sallam said, (three times), "The Religion is nasihah (sincerity and sincere advice)." We said, "To whom?" He said, "To Allah, His Book, His Messenger, and to the leaders of the Muslims and the general people." [Related by Muslim (no. 55)]
Commentary
Imam An-Nawawi (d. 676H) - rahimahullah - said:
"As regards sincerity to Allah - the Most High - then its meaning refers back to having iman (faith) in Allah, and the denial of ilhad (denying or altering the meanings) with regards to His Attributes. Describing Him - the Most High - with the qualities of completeness, perfection, and greatness whilst declaring Him completely free from any defects or deficiencies. To avoid disobedience to Him. To love for His sake and to hate for His sake. To keep good relations wit those who obey Him and to have enmity towards those who disobey Him. To perform Jihad against those who disbelieve in Him. To recognize His favours and to give thanks to Him for them. To have sincerity in all affairs. To call to everything that we have mentioned, and to encourage it. To show kindness to all people, to all those whom you are able to, in this call. Imam Al-Khattabi (d. 388H) - rahimahullah - said, 'The reality of this attachment refers back to the servant being sincere to himself, since Allah - the Most High - has not need of the sincerity of the one doing it.'