Allah has mentioned “the illness of hearts and their healing” in several places in His Book, and this also appears in the Sunnah of His Messenger, may Allah bless him and grant him peace. For example, Allah Most High says of the hypocrites:
“In their hearts is a disease, so Allah has increased their disease.”
He says:
“So you see those in whose hearts is a disease rushing to join them.”
Allah Most High says:
“And heal the hearts of a believing people,”
“And remove the anger from their hearts.”
He says:
“There has come to you an admonition from your Lord and a healing for what is in the hearts.”
Allah Most High says:
“We send down of the Quran that which is a healing and a mercy for the believers.”
Allah Most High says:
“Say: For those who believe, it is guidance and healing.”
Allah Most High says:
“Do not be soft in speech, lest someone whose heart is diseased should desire you.”
He says:
“If the hypocrites, those in whose hearts is a disease, and those who spread rumours in Medina do not desist, We will surely incite you against them.”
He says:
“And when the hypocrites and those in whose hearts is a disease said: ‘Allah and His Messenger promised us nothing but delusion.’”
The Prophet, may Allah bless him and grant him peace, said:
“Why did they not ask when they did not know? The cure for ignorance is simply to ask.”
Al-Rashīd said: “Now you have cured me, Mālik.”
In Sahīh al-Bukhārī, Ibn Masʿūd is reported to have said:
“A person continues to fare well so long as he fears Allah and, whenever he is unsure about the meaning of something, asks someone who dispels his uncertainty. Yet soon he will find no such person—by Him besides whom there is no god.”
What Allah mentions concerning the illness of hearts and their healing is comparable to what He mentions concerning their death