Tamim al-Dari reported: The Prophet, peace and blessings be upon him, said, “The religion is sincere good will.” We said, “To whom?” The Prophet said, “To Allah, His Book, His Messenger, the leaders of the Muslims, and their common people.”
Source: Ṣaḥīḥ Muslim 55
Grade: Sahih (authentic) according to Muslim
عَنْ تَمِيمٍ الدَّارِيِّ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ الدِّينُ النَّصِيحَةُ قُلْنَا لِمَنْ قَالَ لِلَّهِ وَلِكِتَابِهِ وَلِرَسُولِهِ وَلِأَئِمَّةِ الْمُسْلِمِينَ وَعَامَّتِهِمْ
55 صحيح مسلم كتاب الإيمان باب بيان أن الدين النصيحة