The ninth day of the sacred month of Muharram [Tasou'a`] is the heartbreaking introduction of Ashura, the calm before storm. As once the 'Asr prayer was finished from the ninth of Muharram, Omar Ibn Sa'd has called: "O horses of Allah ride and with paradise be delighted." People rode their horses and went to attack Imam Al-Hussayn (peace be upon him) and his companions, while Imam Al-Hussayn (peace be upon him) was sitting in front of his tent, leaning on his sword, once he has seen them he stood up and said: "O Abbas, mount your horse -may I be your redemption O brother- and go to meet them and tell them: What do you have and what do you want? Al-Abbas (peace be upon him) went and asked them and they replied: We received the order of the commander to to fight you or to take from you the oath of allegiance. Al-Abbas (peace be upon him) went back to inform Al-Hussayn (peace be upon him) with what they have said. Imam Al-Hussayn (peace be upon him) then asked them to give him this night for worship and prayer, so the next day they can fight.
On the afternoon of that day, once Zaynab (peace be upon her) heard the sounds of the attackers, she quickly went to awaken the Imam to inform him about the move of the enemy's army, saying: "O my brother, Do you hear these sounds approaching?". Imam Al-Hussayn (peace be upon him) raised his head and told her: "I just have seen the Messenger of Allah (Allah's prayers be upon him and his holy Household) in the dream telling him: "you are coming to us." She slapped her face and called the woe. Imam Al-Hussayn (peace be upon him) told her: "The woe is not to you dear sister, shut up God have mercy on you."
After the sunset, Imam Al-Hussayn (peace be upon him) led the obligatory prayers with his companions. As soon as the prayers were finished, Imam Al-Hussayn (peace be upon him) made a speech before his companions. First, he praised the Lord for giving so many sincere companions and friends. He then said, “I am thankful to you all for your affection and your willingness to help me at this hour. But, I assure you that Yazid is only thirsting for my blood. I hereby discharge you from the obligation under your pledge of allegiance to me and I release you from all bonds you pledged to assist me. I like that you leave me now and go back to your homes. I shall not hold you responsible if you go away now, as it is now not obligatory for you to remain with me. If you feel shy to leave before my eyes, I will make it easy for you by putting out the lights so that, in the darkness, nobody can see who has left the camp.”
So saying, Imam Al-Hussayn (peace be upon him) snuffed out all the lights and darkness enveloped for a long time. At that time, there were few hundred persons besides Imam Al-Hussayn (peace be upon him), but, when the lamps were lit, only fifty-four companions remained, in addition to Imam Al-Hussayn’s kith and kin. Those who remained with Al-Hussayn (peace be upon him) were resolute about sacrificing their lives for the cause of the Imam of the day. Imam Al-Hussayn’s brother, Al-Abbas (peace be upon him) said, “Woe to the life without you!”
Historians like Dahhak Ibn Abdallah Al-Mashriqi record that throughout the night, supplications and prayers and frequent cries of ‘Allaho Akbar’ were reverberating along with the wailing of the thirsty children demanding water with their mothers trying to console them, that Imam Husain’s camp sounded like a busy bee hive.
It is narrated that Imam As-Sadeq (peace be upon him) said: "Tasu'a` is the day in which Al-Hussayn and his companions were besieged in Karbala by the people of Syria on their horses from all sides and offloaded their luggage. The son of Marjanah (Ubaydullah bin Ziyad) and Omar ibn Sa’d were pleased at the large number of their army and they deemed Imam and his companions to be weak. They knew that Imam Al-Hussayn had no helpers or aides in Iraq. May my father be ransom upon the oppressed traveler. Omar Ibn Sa'd then wetn to attack Al-Hussayn's tents after 'Asr and called his army: "O horses of Allah ride and with paradise be delighted."(woe and maledictions of Allah upon them) Imam Al-Hussayn (peace be upon him) then asked them to give him this night for worship and prayer, so the next day they can fight..."