What did al-Ghazali say about hypocrisy (nifāq)?

"When a servant is free from any of these, even if he thinks he is, it is hypocrisy. It is said that whoever feels secure from hypocrisy is a hypocrite. One of the wise was told by someone, "I fear hypocrisy in myself. He replied, "If you were a hypocrite, you would not fear hypocrisy. Thus, the knowledgeable person remains in constant fear, balancing between past and future actions, as the Prophet (peace be upon him) said: The believing servant stands between two fears: one concerning a past lifespan, not knowing what Allah has decreed, and one concerning a remaining lifespan, not knowing what Allah will judge."

"and a time comes upon it when it fills with hypocrisy so that faith finds no space like the eye of a needle. Thus you know from this that the fear of the knowers concerning a bad ending and its cause is prior matters, including innovations. Among these are sins and hypocrisy. When a servant is free from any of these, even if he thinks he is, it is hypocrisy. It is said that whoever feels secure from hypocrisy is a hypocrite."

"Al-Hasan said, "Part of hypocrisy is the difference between tongue and heart, secret and openness, entrance and exit." A man said to Hudhayfah, may Allah be pleased with him, "I fear I might be a hypocrite. Hudhayfah replied, "If you were a hypocrite, you wouldn't fear hypocrisy. The hypocrite feels safe from hypocrisy.""

"When he prays, let him lower the curtain of his door, for Allah apportions praise as He apportions provision. Our Prophet (peace be upon him) said, “Allah, the Almighty, does not accept an action with the weight of an atom of riya [showing off]. The hadith of Mu'adh, “Even a bit of showing off is shirk,” was recorded by al-Tabarani and al-Hakim with the wording, “The slightest bit of showing off is shirk,” and it was mentioned earlier."

"Ibrahim ibn Adham said, "The one who desires fame has not been truthful to God." Explanation of the True Nature of Riya and What is Intended by It: Know that 'riya' (showing off) is derived from 'seeing,' and 'fama' (reputation) comes from 'hearing. Essentially, 'riya' is about seeking stature in people's hearts by displaying acts of goodness."

"The believer feels secure from everyone except Allah, while the hypocrite fears everyone except Allah. The believer prioritizes his wealth over his religion, but the hypocrite prioritizes his religion over his wealth. The believer does good and weeps, while the hypocrite does wrong and laughs. The believer loves seclusion and solitude, whereas the hypocrite loves social interaction and gatherings."

"until he is recorded with Allah as a liar. The Prophet, peace be upon him, also said, the sign of a hypocrite is three. Even if he prays and fasts and claims to be a Muslim, when he speaks he lies. When he makes a promise he breaks it. And when he is entrusted he betrays. He further stated, whoever possesses four traits is a pure hypocrite. And whoever has one of them has a trait of hypocrisy until he abandons it. When he is entrusted he betrays. When he makes a covenant he is treacherous. When he disputes he is wicked. In a hadith from Sahih al-Bukhari, the Prophet, peace be upon him, described a dream. We came across a man lying on"

"Others would deliver it to the poor person's hand through another, instructing the intermediary to keep it confidential, all in an effort to quench the wrath of the Lord and as a precaution against showing off and seeking reputation. If it can only be accomplished by making one person aware, handing it over to an agent to deliver it to the needy is preferable to knowing the needy directly, for it involves showing off and belittling, whereas knowing the intermediary involves only showing off."

"None of them said that his faith was like that of جِبْرِيل and مِيكَائِيل." البُخَارِيّ mentioned this, and it was reported from الحَسَن البَصْرِيّ: "No one feels safe from it except a hypocrite, and no one fears it except a believer." It was mentioned about some of the companions that he would say in his supplication: "O اللّٰه, I seek refuge in You from the humility of hypocrisy." When asked what the humility of hypocrisy was, he said: "That the body appears humble while the heart is not.""

"This does not necessarily mean singing is prohibited. Wearing fine clothes, riding well-trained horses, and other forms of adornment can also plant hypocrisy and showiness in the heart, yet they are not prohibited. Hypocrisy can arise from permissible activities that are prominently observed by others. Umar, may Allah be pleased with him, once dismounted a well-groomed horse and cut its tail because he felt pride in its beauty, showing that even permissible actions can lead to hypocrisy."