Sunan an-Nasa'i 4200
سنن النسائي#4200SahihIt was narrated from Abu Hurairah that the Messenger of Allah said:"Religion is sincerity (An-Nasihah)." The said: "To whom, O Messenger of Allah?" he said: "To Allah, to His Book, to His Messenger, to the imams of the Muslims and to their common folk
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahHasan Sahih
Al-AlbaniHasan Sahih
Zubair Ali ZaiHasan
In-book reference: 39:52