Praise be to Allah, the Lord of the Worlds, and peace and blessings be upon His Messenger. Afterwards:
Allah has made advice a fundamental principle of religion, and indeed, the Prophet, peace be upon him, stated that it is the very essence of religion. This is because its benefits extend to all people, beginning with the one who gives advice, who purifies his own religion and seeks the highest of matters, and ending with the one who receives the advice and benefits from it by being protected from harm. The Messenger of Allah, peace be upon him, said: "Religion is advice." We asked: "To whom?" He replied: "To Allah, to His Book, to His Messenger, to the leaders of the Muslims, and to the common people of the Muslims." [Agreed upon].
Advice means guidance towards that which is beneficial. It is to guide someone towards the right path and to encourage them to do good deeds that will bring them happiness and success. It is also to enlighten someone about the dangers so that they may avoid them. Advice is one of the duties of prophets and a characteristic that distinguishes them. Allah Says (What means): "And I said: 'O my people, I have indeed conveyed to you the message of my Lord and have given you sincere advice." [Al-A'raf/79].
Allah has commanded us to emulate the character of these prophets, peace be upon them, and to follow their example in giving advice and guidance. This is the way of Allah with His righteous servants. Al-Hasan al-Basri said: "There have always been people for Allah who give sincere advice to Allah concerning His servants, and give sincere advice to the servants of Allah concerning the rights of Allah upon them, and work for Him on earth with sincerity. These are the successors of Allah on earth." [Lata'if al-Ma'arif by Ibn Rajab].
Advice is one of the most important matters that Allah has obligated upon Muslims so that their lives may be upright and none of them may deviate. Jarir Ibn Abdullah reported: "I pledged allegiance to the Messenger of Allah, peace be upon him, to establish prayer, pay Zakat, and give sincere advice to every Muslim." [Agreed upon]
And because "a Muslim is the mirror of his brother" - as the Prophet, peace be upon him, informed us (as narrated by Ibn Khuzaymah) - it is the right of one Muslim upon another to be sincere towards him in all matters of his life and to desire good for him in his religion, his worldly life, and his livelihood. The Messenger of Allah, peace be upon him, said: "The rights of a Muslim over another Muslim are six." It was said: "What are they, O Messenger of Allah?" He replied: "If you meet him, greet him, and if he invites you, accept his invitation, and if he seeks your advice, advise him, and if he sneezes and praises Allah, then greet him, and if he falls ill, visit him, and if he dies, attend his funeral." [Moslim]. In addition, among the supplications of the Prophet, peace be upon him, was: "O Allah, set right for me my religion that is the safeguard of my affairs, and set right for me my world wherein my living is, and set right for me my Hereafter wherein my return is, and make life an increase for me in every good, and make death a relief for me from every evil."
Therefore, a Muslim who gives sincere advice to his brothers and desires good for them, and is safe from their tongues and hands, has fulfilled his duty. The Prophet, peace be upon him, said: "The Muslim is he from whose tongue and hand the Muslims are safe." [Agreed upon]. Safe from his tongue means that he does not backbite them, mock them, or impose upon them that which causes them embarrassment or hardship.
It is also incumbent upon a person to begin giving advice to himself, out of commitment and application, so that he may not be among those about whom Allah Says (What means): "Do you order people to be righteous while you forget yourselves, even though you recite the Book? Then will you not understand?" [Al-Baqarah/44]. Abu Bakr Al-Ajurri said: "No one can be sincere to Allah, His Messenger, the leaders of the Muslims, and the common people of the Muslims except the one who begins with giving sincere advice to himself and strives in knowledge and understanding, so that he may know what is obligatory upon him, and know the enmity of Satan towards him and how to be wary of him, and know the ugliness of that to which the soul inclines so that he may oppose it with knowledge."
Sincere advice should be purely for the sake of Allah so that the Muslim may obtain its reward and recompense. It should be given with gentle words that are accepted, and in a manner that is befitting of a reformer who is concerned for his brothers. It should also be given in private and according to the situation, so that it does not become a public humiliation that causes the one who receives the advice to become stubborn and increase in his error and sin. Imam Al-Shafi'i said: "Advise me privately, and spare me from giving advice in public, For advising people in public is a kind of rebuke that I do not enjoy hearing."
All praise is due to Allah, the Lord of the Worlds.