For the sake of brevity, I will cite the most important reason for this practice and that is that Imam Hussain’s martyrdom is part of the prophetic legacy (Sunnah). God, in many Quranic verses, has commanded Muslims to follow the example of the Prophet. For instance in one verse God Almighty says:

“Certainly you have in the Messenger of God an excellent exemplar for him who hopes in God and the last day and remembers God much.” Quran 33:21

Al-Hakim al-Nisapouri (d. 405 AH) in his most famous Hadith collection known as Al-Mustadrak `alâ al-Sahîhayn (“Supplement for What is Missing From al-Bukhârî and Muslim”) reports:

“Ummul Fadhl, the daughter of al-Harith said that she entered on the Messenger of God and she said: “O Messenger of God, I saw a strange dream last night. He said: And what is it? She said: It was difficult. He said: And what is it? She said: I saw, as if, a piece of your body was severed and was put in my lap! The Messenger of God said: You saw something good- Fatima will give birth, God willing, a boy so he will be in your lap. Then Fatima gave birth to Hussain (and he was in my lap – just as the Messenger of God said. So I entered one day on the Messenger of God and put him in his lap, but I noticed that the eyes of the Messenger of God pouring tears! So I said: O Prophet of God, my parents are your ransom, what is wrong? He said: Gabriel came to me and informed me that my nation will kill this son of mine.”

Source: al-Mustadrak al-Sahih, al-Hafidh al-Hakim al-Nisapouri, v. 3, p. 176, (al-Hakim said: “This is an authentic hadith (Sahih) on the conditions of Bukhari and Muslim but they did not print it”)

From this narration, we understand that the Prophet wept for Hussain nearly 50 years before his martyrdom! If the Prophet wept for him before his tragic martyrdom, don’t blame us for weeping for him after his heart wrenching martyrdom.

Why do we cry for Imam Hussain you ask?
Put simply, we cry for Hussain because the Prophet (s) did.

Answered by: Shaykh Azhar Nasser