Not grieving over missed good deeds and not feeling remorse for one's mistakes are among the signs of the death of the qalb (the heart).
Verse Translation
If the heart is dead, it feels no sorrow for missed acts of obedience
Nor does it ever show remorse for committed faults
Takalluf: To be ostentatious. To strive for show. Affected manner and behavior.
Explanation
Not being saddened by missed acts of worship and not feeling remorse for committed sins are signs of the spiritual death of the qalb. Accordingly, being pleased with good deeds and saddened by evil acts are definitive proofs that testify to the true life of the qalb. For this reason, it is said: "Whoever is pleased with the good he has done and saddened by his bad deeds is a perfect mu'min (believer)!" The wisdom in citing good and bad deeds as evidence for the life or death of the qalb is that deeds indicate either Allah's riḍā (contentment with God's decree) or His wrath. For if Allah (may He be exalted) enables a believing servant to perform good deeds, this is a sign of divine contentment and thus requires joy, so hope predominates in that person. And if Allah does not keep that believing servant within the sphere of His protection and makes him bold in committing sins, then, as this is a sign of divine wrath, sorrow and grief become necessary, and fear outweighs hope in him.
Hope does not mean to regard missing acts of worship as insignificant, nor should fear drive a person to such despair that he cannot feel sorrow and seek forgiveness for sins committed out of human weakness.
In this context, rejoicing in good deeds and grieving over evil acts is the hallmark of the awliyāʾ (friends of God) and murīd (aspirants) who love Allah. In the following hadith reported from the Messenger of God (peace and blessings be upon him), the sign and state of the 'people of will' are beautifully described, and thus it is included and reiterated on this page. The narrator of the hadith, the noble Companion (ṣaḥāba) ʿAbdullāh ibn Masʿūd (may Allah be pleased with him), relates: "One day we were in the luminous presence of the Messenger of God (peace and blessings be upon him). Suddenly, a man appeared. He approached us, and after seeing the Messenger of God (peace and blessings be upon him), he made his camel kneel and walked toward the Prophet. When he reached him, he said with utmost respect: 'O Messenger of God! I have come from a journey of nine days. For six days I have traveled by day without water and by night without sleep, in order to present to you two matters that have deprived me of sleep and plunged me into deep thought!' When the Prophet asked who he was, he replied that he was known as Zayd al-Khayl. The Prophet, the Light of the Worlds, said: 'No, you are not Zayd al-Khayl, but surely Zayd al-Khayr! I have been asked many difficult questions before. Tell me your difficulties!' Then Zayd continued and asked about the attributes of those endowed with divine will (irfan, spiritual knowledge), those not endowed with will, and the sign of Allah's decree upon them. The Prophet appreciated his question and, to guide him, asked how he spent his nights and how he greeted the morning. Zayd replied that he loved goodness, good people, and good deeds; that he was saddened if he missed any good or virtuous act; and that when he performed even a small righteous deed, he would rejoice in its reward as he greeted the morning. The Messenger of God said: 'O Zayd! This is the sign of the state resulting from the reflection of divine will. If Allah had willed something else for you, He would have prepared you for that, and you would not have cared in which valley you perished!' Upon this, Zayd al-Khayr said that the answer was sufficient to resolve his difficulty and immediately set out to return without delay."