On the authority of Tameem ibn Aus ad-Daree (may Allah be pleased with him):

The Prophet ﷺ said, “The deen (religion) is naseehah (advice, sincerity).” We said “To whom?” He ﷺ said “For Allah, His Book, His Messenger, and to the leaders of the Muslims and their common folk.”

[Muslim]

عَنْ أَبِي رُقَيَّةَ تَمِيمِ بْنِ أَوْسٍ الدَّارِيِّ رَضِيَ اللهُ عَنْهُ أَنَّ النَّبِيَّ ﷺ قَالَ: "الدِّينُ النَّصِيحَةُ." قُلْنَا: لِمَنْ؟ قَالَ: "لِلَّهِ، وَلِكِتَابِهِ، وَلِرَسُولِهِ، وَلِأَئِمَّةِ الْمُسْلِمِينَ وَعَامَّتِهِمْ." [رَوَاهُ مُسْلِمٌ]