It was narrated that Tamim Ad-Dari said:"The Messenger of Allah said: 'Religion is sincerity (An-Nasihah).' They 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
Hadith No. 4197
Sunan an Nasai
Gradings:
Abu Ghuddah:
Sahih
Al-Albani:
Sahih
Zubair Ali Zai:
Sahih Muslim