Habeeb Ibne Mazahir was about the same age as Imaam Hussain. They were childhood friends. When Hazrat Ali moved the capital to Kufa, Habeeb also moved to Kufa. He stayed on in Kufa and became a prominent citizen. He was a devout Shiah.The first letter which Imaam Hussain received inviting him to Kufa was signed by Habeeb Ibne Mazahir. After Hazrat Muslim and Hazrat Hani Bin Urwah were killed by Ibne Ziyaad, Kufa was sealed off. No one could get in or out of the city without the Governor's permission.
Ibne Ziyaad also started spreading the rumour that Imaam Hussain had gone to Madina and that he was living there happily under the protection of Yezid. Even Imaam Hussain's messenger Qais Bin Musheer who tried to take a letter to the citizens of Kufa was arrested outside Kufa. He was tied and gagged, and thrown from the roof of the palace to the ground three times. Ibne Ziyaad succeeded in spreading terror in Kufa and silencing the people.
Habeeb Ibne Mazahir was heart-broken because he could not join Imaam Hussain. He did not even know where Imaam Hussain was. There were all sorts of rumours but no one knew anything for certain.
Imaam Hussain had reached Kerbala. Everyday Bibi Zainab saw soldiers coming to join the camp of Umar-e-Sa'ad, the Commander of Yazeed's Army. On 4th Muharram she came to Imaam Hussain and said "Ya Akhee, why are all these soldiers coming?". Imaam replied "My dear sister, they are gathering to kill me". Bibi Zainab said, "Brother, you have hardly seventy-two men with you, while they are in thousands". Bibi Zainab had tears in her eyes as she added, "Do you not have anyone ready to come to your help?". Imaam Hussain said "Falsehood can buy you many supporters, truth has few friends".
That very day Imaam Hussain wrote a letter to Habeeb Ibne Mazahir, his childhood friend, telling him how Yezid's vultures were gathering to kill him. The letter was carried by a messenger who entered Kufa in the dark by climbing over the city walls. The messenger reached Habeeb's house as Habeeb, his wife and his young son were sitting down for breakfast. Habeeb read the letter, kissed it and tears began to flow down his cheeks. His wife asked him what was wrong. Habeeb said "Who would ever have thought that people would be so thirsty for the blood of the grandson of the Holy Prophet, whose name they utter in every Adhaan and in every Salaah?"
Habeeb instructed his servant to take his horse to a farm outside the city and wait for him there. If anyone should ask, the servant should say that he was taking the horse for grazing.
At Asr, when most people were in the mosque Habeeb slipped out of Kufa. He mounted his horse and galloped towards Kerbala. Habeeb Ibne Mazahir reached Kerbala late in the evening. Imaam Hussain greeted Habeeb with great affection. When Bibi Zainab heard that Habeeb had come she asked Janaab-e-Fizza to convey her greetings to Habeeb. When Habeeb received the message he began to sob saying, "How fortunate are the companions of Imaam Hussain that the daughter of Fatimah Zahra should honour them with greetings".
On the fateful day of Ashura, between zuhr and asr, Habeeb Ibne Mazahir rode into the battlefield. He fought bravely. Finally he was over-powered, He fell to the ground. Imaam Hussain rushed to him. Habeeb looked at Imaam and said "O the grand-son of the Holy Prophet, please forgive this humble servant for not being able to give more than his unworthy life for you and Islam". Imaam took Habeeb in his arms and cried, "O my friend! O my friend!". Habeeb died resting his head on Imaam's shoulder.
Taken from 'Journeys of Tears'