Dr. Nasim Rehmatullah - Naib Amir USA & Chairman Markazi Al Islam Team
Published: November 12, 2025
The Arabic language's richness is nowhere more evident than in the Quran's precise vocabulary. When describing the human heart, Allah uses three distinct terms, qalb, fu'aad, and sadr, each revealing profound insights into our spiritual and emotional states.
Qalb appears 132 times in the Quran and serves as the general term for heart. Its root meaning "to turn" captures an essential truth: hearts are inherently inconstant, perpetually fluctuating between states of faith and doubt, obedience and rebellion. This is why the Prophet (sa) frequently made the supplication: Yā muqalliba al-qulūb, thabbit qalbī 'alā dīnik (O Turner of hearts, make my heart firm upon Your religion).
When Allah speaks of iman (faith) and spiritual diseases, He uses qalb. The Promised Messiah (as) explained that the qalb is the seat of understanding and recognition of divine truth, emphasizing that true transformation occurs when this ever-changing heart becomes firmly anchored in faith. It is the heart with which the line of divinity is linked.
Fu'aad derives from fa'ada, meaning "to burn" or "to flame" as in lahmun fa'eed (roasted meat). This term describes a heart consumed by intense emotion, whether joy, grief, desire, or anguish.
Allah uses fu'aad when describing Umm Musa's emotional state: "But there came to be a void in the heart (fu'aado) of the mother of Musa" (28:11). Having placed her infant in the Nile, her heart burned with such overwhelming anxiety that it became faarigha (empty), unable to contain any thought beyond her son's fate. Yet moments later, Allah declares: "We strengthened her heart (qalbiha)" (28:11). Once fortified with faith and trust, her burning fu'aad transformed into a steady qalb.
This linguistic shift reveals a profound spiritual principle: emotional turmoil must be tempered by faith to achieve spiritual stability.
Sadr means "chest" and signifies what lies hidden within, our concealed motives, secret intentions, and innermost thoughts. Like a locked treasure chest, the sadr contains what we keep from others and sometimes from ourselves.
In Surah An-Nas, Allah describes Satan as "the one who whispers in the hearts (sudoor) of mankind" (114:6). Critically, Satan whispers not into our quloob but into our sudoor.
The Prophet (sa) said: "Verily, there is a piece of flesh in the body; if sound, the whole body is sound, and if corrupt, the whole body is corrupt. Verily, it is the heart" (Bukhari and Muslim). This hadith emphasizes that while Satan targets our sadr, only we can allow corruption to reach our qalb.
The emphasis is that Allah created the qalb pure and protected. Satan stands outside this fortress, attacking through the gates of our eyes, ears, tongue, and hands. He cannot directly access our hearts. We ourselves open the gates through our choices.
These three terms illuminate our spiritual anatomy. Our qalb fluctuates naturally, this is human nature. Our fu'aad burns with emotion in life's intense moments. Our sadr harbors what we conceal. Understanding these distinctions empowers us to guard our hearts more effectively, remembering that Allah in His mercy has protected our innermost sanctum, requiring only that we vigilantly guard its gates.
