Ibn Masʿūd also said, “Remembrance of Allah (dhikr) makes faith grow in the heart just as water makes herbage grow, whereas singing makes hypocrisy grow in the heart just as water makes herbage grow.”

When a person is versed in the inner realities of faith and can distinguish between states that come from the All-Merciful and those that come from Satan, that is because Allah has cast some of His light into his heart, as He says:

“O you who believe, be mindful of Allah and believe in His Messenger; He will grant you a double share of His mercy, provide you with a light by which you will walk, and forgive you.”

And He says,

“Thus We have revealed to you a spirit by Our command. You did not know what the Scripture was, nor what faith was, but We made it a light by which We guide whom We will of Our servants.”

Such a person belongs to the believers described in the ḥadith transmitted by al-Tirmidhī, on the authority of Abū Saʿīd al-Khudrī, in which the Prophet ﷺ said, “Beware the firāsah (keen insight) of the believer, for he looks with the light of Allah.” Al-Tirmidhī graded this ḥadith as ḥasan (sound).

[The believer distinguishes between the allies of the All-Merciful and the allies of Satan]

We have already cited the sound ḥadith recorded by al-Bukhārī and others in which Allah says, “My servant continues to draw near to Me through supererogatory acts until—”