Giriya wa Matam Ka Tehqiqi Jayeza is an Urdu Research book by Dr. Hakim Mubarak Ali Jafri. In Sura Tauba Ayet 82 says mourn, cry and weep more and laugh low and little. Shiites has another thought about mourning and tears as well as many times they beat their own chest and with iron chains. They say that its a Nature of Human that when he is happy then he smiles or laugh but when he is grieved or in sorrow then it is must that he will cry, will weep and many times scream/squeak out. So when they weep or cry by remembering martyrdom of hussain a.s and other his companions, it is according to nature, it is our love and devotion for Muhammad PBUH and his family.