Today/Tommorow [depending on how you follow the moon and your particular madhab/sect], hundreds of millions of muslims will be commemorating the brutal slaughter and massacre of the Grandson of Muhammed s.a.w, Hussain ibn Ali a.s, along with many other descendants of Muhammed s.a.w and the banu-hashim and their companions.
What is it about?
For one to begin to examine why Hussain , the grandon of Rasulullah s.a.w rose up, we must first take a step back and reflect on the political arena at the time. The despotic ruler was a tyrant who went by the name of Yazid , the son of the previous caliph, Muawiyah, the son of the fierce enemy of Muhammed s.a.w, Abu Sufiyan.
Now, Yazid ibn Muawiyah abandoned many of the essential principles and tenants of Islam. He was a wild drunkard, a ruthless ruler, despotic, and unlike his father, had very little political awareness and had terrible judgement. From his attack on the K'aba , to a number of atrocities committed during his life time [least of all slaughtering Hussain a.s and the family of Muhammed s.a.w], by his abandoning of Islam and terrible decisions and ruling, the threatened to unravel the religion, step by step.
In order to try and gain some legitimacy, he forced and would coerce prominent and well known people, a number sahaba, to give him the oath of allegiance, thus, giving him a false air of legitimacy.
Hussain ibn Ali a.s knew full well - as did those with him- that giving Yazid this Bayah, especially a personality with such prestige, garnering such widely held respect, even among his enemies, as Hussain ibn Ali a.s had, it would have given Yazid the lisence to carry on as he willed. He was young at the time, and may have ruled decades on [a frightening prospect].
By refusing to give him the oath of allegiance, and having his own body slaughtered mercilessly, as well as the death of even a six month old child whose neck was pierced by a three-pronged arrow, his stand and sacrifice sent a message that reverberated far and wide, laying the foundation that would then be the fall of Yazid, and setting a template against despotic rulers.
Why commemorate?
It is widely accepted, in both shia and sunni circles, that Muhammed s.a.w, the greatest creation, the greatest man to have walked this earth, a man whose very actions and way of life we yearn to aspire to and follow, even in the most minute detail, was forewarned about this tragedy. Indeed, it saddened him and some reports narrate him shedding tears. It broke his heart to see what his own Ummah would do to his grandson.
"...the Prophet ṣallallāhu 'alayhi wa sallam (peace and blessings of Allāh be upon him) said to one of them [either Aisha or Umm Salamah raḍyAllāhu 'anhum (may Allāh be pleased with them)], “An angel entered the house on me, he never entered on me before, and he said to me, 'this son of yours, al-Hussain, will be killed, and if you wish I can show you the soil from the earth where he will be killed'. Then he took out some red soil”. [Recorded in Musnad al-imam Ahmad, vol. 6 p. 294]
Sheikh Al-Albani says: “Altogether, the Hadith is authentic by collectively considering all the chains of narration. This is true even though each single chain is not free from defects, but it's minor defects. This is not to mention that some of those chains were graded as Hassan [less authentic than Sahih, yet authentic] by al-Haythamee. And Allah knows best.”
Hussain ibn Ali a.s was the sweet basil of Muhammed s.a.w. He is one of the leaders of the youths of paradise [we will all enter as youths]. He was a Sahaba, and above that, a man attaining the rank of Ahlulbayt. One who, along with Hasan a.s, was taken to the event of Mubahila, to represent the muslims, as the 'sons' of Rasulullah against the christians of Najran.
His death so monumental, even the angels go to Rasulullah s.a.w and show them the red soil inwhich he will be martyred.
Closing:
The heart-wrenching events that occurred in Kerbala would cause even one not acquainted with who Hussain ibn Ali a.s was shed a tear. But for one who knows his position, and recognizes the full effects of his sacrifice, a glowing sense of appreciating at this selfless grandson of the holy prophet s.a.w emerges.
His stand and sacrifice is not one that should be simply read as an event from the books of history. Rather, is is a lesson, that must be renewed, year after year, and in his example we must aspire, or try to follow.