It is narrated from Sayyiduna Sufyan bin Abdullah Thaqafi (may Allah be pleased with him), he says: I said, "O Messenger of Allah! Tell me something about Islam such that after you (Abu Muawiyah has narrated the words 'after you'), there remains no need to ask anyone else about it." The Prophet (peace and blessings be upon him) said: "Say, 'I believe in Allah,' and then remain steadfast upon it."

(Second chain of narration) I said: "O Messenger of Allah! Tell me something to which I may hold fast (and be diligent about it)." He صلی اللہ علیہ وسلم said: "Say: My Lord is Allah, then remain steadfast upon it." I said: "O Messenger of Allah! Of what are you most afraid for me?" In response, he صلی اللہ علیہ وسلم held his tongue and said: "This."

It is narrated from Sayyiduna Abdullah bin Mas’ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said:“Indeed, just as Allah Almighty has distributed your sustenance among you, likewise He has distributed your character among you. And indeed, Allah Almighty grants the world to the one He loves and also to the one He does not love, but He grants the blessing of religion only to the one He loves. Whoever Allah Almighty has granted religion, it means that Allah Almighty loves him. By the One in Whose hand is my soul! No one can be a Muslim until his heart and tongue become obedient, and no servant can be a believer until his neighbor is safe from his evils.”The people asked:“O Messenger of Allah! What is meant by ‘evils’ (bawa’iq)?”He (peace and blessings be upon him) said:“His oppression and excesses. And whoever earns unlawful wealth and spends it, there will be no blessing in it, and any charity given from it will not be accepted, and if such a person leaves behind any such wealth in his inheritance, it will be his provision for Hell. Indeed, Allah Almighty does not erase evil with evil, rather He erases evil with good, and indeed, an impure thing cannot erase another impure thing.”(Sins are not erased by spending unlawful wealth, rather sins are cleansed by spending lawful wealth.)

It is narrated from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that when he asked the Messenger of Allah (peace and blessings be upon him) about the best form of faith, the Prophet (peace and blessings be upon him) said: "It is that you love for the sake of Allah Almighty, hate for the sake of Allah Almighty, and keep your tongue engaged in the remembrance of Allah Almighty." He said: "O Messenger of Allah! Say more." The Prophet (peace and blessings be upon him) said: "And that you like for people what you like for yourself, and dislike for them what you dislike for yourself." In another narration: "And say good words or remain silent."

It is narrated from Sayyiduna Abbas bin Abdul Muttalib (may Allah be pleased with him) that he heard the Messenger of Allah (peace and blessings be upon him) saying: "That servant has tasted the sweetness of faith who is pleased with Allah as his Lord, Islam as his religion, and Muhammad (peace and blessings be upon him) as his Prophet and Messenger."

It is narrated from Sayyiduna Abu Musa Ash'ari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "He who is pleased when he does a good deed and is distressed when he commits a bad deed, he is a believer."

Sayyiduna Amir bin Rabi’ah (may Allah be pleased with him) has also narrated a similar type of hadith from the Noble Prophet (peace and blessings be upon him).

Sayyiduna Abu Umamah (may Allah be pleased with him) narrates that a man asked the Noble Prophet (peace and blessings be upon him): "What is sin?" He (peace be upon him) replied: "When something causes uneasiness in your heart, then leave it." He asked: "What is faith?" He (peace be upon him) replied: "When your evil deed displeases you and your good deed pleases you, then you are a believer."

It is narrated from Sayyiduna Anas bin Malik, may Allah be pleased with him, that the Noble Prophet, peace and blessings be upon him, said: "By Him in Whose hand is my soul! No servant can be a believer until he desires for his brother what he desires for himself of goodness and virtue."

Sayyiduna Abdullah bin Amr bin al-As (may Allah be pleased with them both) narrates that a man said: "O Messenger of Allah! Which Islam is the best?" He (peace be upon him) said: "The Muslim from whose tongue and hand other Muslims are safe and secure."