It is due to the objection regarding this matter. (Ravza, 651)
Ḥuzn (spiritual sorrow) is the breaking of the qalb (the heart) and its humility (khushūʿ). Its sign is that, for the breaking of the inner self, the outward limbs lose their expansiveness (inbisāṭ, i.e., ease and freedom of movement). Three characteristics bring about ḥuzn: reflecting on past sins, contemplating death, and looking at those who are more muttaqī (possessed of greater taqwa, God-consciousness) than oneself.
One of the Sufis has said: Ḥuzn is the effect of fear of Allah, the Exalted. Therefore, the illumination of the qalb is realized through these two things (khawf [fear] and ḥuzn), just as its ruin is realized through joy and heedlessness (ghafla). (Câ, 210)