On the authority of Tameem ibn Aus ad-Daree (ra): The Prophet (ﷺ) said, “The deen (religion) is naseehah (advice, sincerity).” We said, “To whom?” He (ﷺ) said, “To Allah, His Book, His Messenger, and to the leaders of the Muslims and their common folk.” [Muslim]
Forty Hadith of an-Nawawi · no. 7