Akfāl-i kulūb (locks upon the hearts) refers to the rusting of the qalb (the heart) due to heedlessness, error, opposition, and betrayal, such as the abundance of sins, following caprice, love of dunyā (the world), prolonged heedlessness, intense greed, attachment to comfort, and delight in praise and exaltation. (Lumaʿ, 147)
(See also: ḥijāb; qalb; reyn/rān)