Advice From the Salaf, Advice to the Students of Knowledge and the Du'aat (Callers to Islaam), Advice to the Muslims and the Methodology of Giving Advice.
From Tameem ad-Daaree who said: Allaah's Messenger (Sallallaahu 'Alayhi Wa Sallam) said: The Religion is sincerity. The Religion is sincerity. The Religion is sincerity. We said: For whom, O Messenger of Allaah (Sallallaahu 'Alayhi Wa Sallam) He said: For Allaah, and His Book, and His Messenger, and for leaders of the Muslims, and their general masses. [Related by Muslim-Kitaabul Eemaan (33, 55) and (1/74). Abu Daawood (no. 4944), (5/233). Ahmad (4/102-103). Nisaa`ee (7/140)]
al-Haafidh Ibn Hibbaan said: The faithful and sincere adviser has a distinguishing sign: when he wishes to enhance the one whom he is advising, he advises him privately. However, the sign of the one who wishes to disgrace him is that he advises him in public. [Rawdatul Uqalaa (p. 196)]