Sayyiduna Anas ibn Maalik [Radhiallaahu anhu] reports that Rasulullah [Sallallaahu Alayhi Wasallam] said, ‘The inability to weep is due to committing excessive sins. That is due to not fearing Allah which results in the hardness of the heart. The hardness of the heart is caused by the love of the world.’ (Musnadul Firdaws vol.4 pg.402; Hadith6690)