She was born in Medina on the 5th of the month of Jamadi al-Awwal in the 6th year of the Hijra. Prophet Muhammad (PBUH) was overjoyed at the birth of his first grand daughter and named her Zainab, which means Ornament of the Father. The loving father, Imam Ali ibn Abi Taleb (A.S) was overjoyed as well and so was the mother, the Prophets daughter Hazrat Fatima Zahra (A.S).
The newborn grew into a virtuous girl imbibing from her parents and her grandfather, the values that would stand out in Karbala and make her carve an eternal place in world history. Her personality was shaped by the teachings of her peerless mother. In fact, in merits she was second only to Hazrat Fatima (A.S), the greatest lady of all time. Hazrat Zainab (A.S), it is said bore a striking resemblance to her maternal grandmother, the late Hazrat Khadija al-Kubra (A.S), the lady who sacrificed all her proverbial wealth for Islam in the days of persecution of Muslims. In her paternal grandmother, Hazrat Fatima bint-e Asad (A.S) she had another great lady of Islam who had brought up the prophet as her own son when he was orphaned in boyhood. Thus, it could be said, virtue and greatness flowed in the veins of Hazrat Zainab (A.S).
In 11 AH, the 5-year old Zainab (A.S) lost her grandfather and mother within the space of 95 days. Her father, Imam Ali (A.S), whose valour, insight, wisdom and eloquent power of speech she inherited, now directly groomed her to the extent that she became known as Aqeelat al-Bani Hashem or the Wise Lady of the Hashemite Clan. Her great knowledge could be gauged from the fact that her brothers Imam Hassan and Imam Hussein (peace upon them) always held their sister in high respect. She was married to her first cousin Abdullah ibn Jafar and became the mother of three sons and a daughter. But family life did not stop her from assuming an active role in society as the Teacher of the Women of Medina. She used to impart them the ethereal values of Islam and give a rational explanation of the Gods words, the Holy Qur’an, as revealed to her grandfather Prophet Muhammad (blessings of Allah upon him and his progeny). Although her husband was a wealthy and generous man, Hazrat Zainab (A.S) was never attached to material life. She devoted her entire life to the welfare of Muslims and undeterred by the massacre of her household at Karbala that included the martyrdom of her two youthful sons, Aun and Muhammad, she bravely confronted the tyrant Yazid, the perpetrator of history most heart-rending tragedy. It was for this reason she had accompanied her brother Imam Husain (AS) on his fateful journey.
When marching out for his final stand at Karbala, Imam Hussein (A.S) entrusted to the care of his sister the entire undefended including his bed-ridden 23-year old son and successor, Imam Zain ol-Abedin (A.S). The Lady, who thanked God for accepting her sacrifice on the martyrdom of her two sons, saw the sanguine spectacle of the martyrdom of her loving brother Imam Hussein (A.S). O Sister! Do not forget me in your late midnight prayer, said the Imam, and Zainab (A.S) despite the hardships of imprisonment that she endured after the tragedy of Karbala, never neglected the late midnight recommended prayer. In captivity she triumphed and carried the struggle to the enemy’s camp.
Her wise and eloquent speeches along with those of her enchained nephew Imam Zain ol-Abedin (A.S) unmasked the crimes of the godless Omayyad regime and awakened people towards the message of the uprising of Imam Hussein (A.S). He had refused to yield to tyranny and the sister conveyed this heroic stand in the courts of Kufa and Damascus, by refusing to be buckle down to oppression and calling all that she had been through as: I see nothing but the beauty of God Almighty. She thus popularized the mission of her martyred and as part of her efforts to nurse back Islam to life, the Prophets granddaughter upon release from imprisonment laid the foundations of the life-inspiring mourning ceremonies, which the faithful have continued to hold regularly ever since in the months of Muharram and Safar.
source : tebyan