Hz. Zaynab was the oldest daughter of the Prophet (pbuh). She was born when the Prophet was 30 years old. She was 10 years old when Hz. Muhammad (pbuh) was given the duty of prophethood. She became a Muslim together with Hz. Khadija.
When she reached the age of marriage, he married her off to Abul As bin Rabi acting upon the request of Hz. Khadijah. Abul As was the son of Hala, who was the sister of Hz. Khadijah. He had not become a Muslim yet. At that time, there was no decree prohibiting a Muslim woman from marrying a polytheist.
Hz. Zaynab felt very sad because the polytheists tortured his father. However, the Prophet advised her not to feel sad. When the Prophet migrated to Madinah, Hz. Zaynab had to stay in Makkah because her husband did not allow her.
Hz. Zaynab was very sad because she had been separated from her father and she was married to a polytheist. However, she showed patience by relying on Allah. Meanwhile, she always prayed Allah so that her husband would become a Muslim.
Strangely, Abul-As was captivated during the Battle of Badr. The polytheists sent some ransom to the Muslims in order to save the slaves.
Abu’l-As was a polytheist but he was Hz. Zaynab's husband. She wanted to save him but she had nothing to send as ransom. She remembered the necklace her mother had given her when she got married. She sent it with some other small things to Madinah.
When they arrived in Madinah, the Messenger of Allah felt moved. He thought of the assitance of Hz. Khadija to him and the Muslims. He could not help crying and said to his friends, "If you agree I want to return this necklace to Zaynab and release Abu’l As." The Companions said, "Yes, of course, O Messenger of Allah!" They released Hz. Zaynab’s husband and returned the necklace.
Abu’l-As was an honest and trustworthy person. He felt ashamed due to the generosity of the Prophet. He promised that he would release Zaynab when he returned to Makkah. The Prophet sent Zayd bin Haritha and a Companion from Ansar to Makkah to take her to Madinah.
These Companions did not enter Makkah; they started to wait at the Valley of Yajaj. Abu'l As sent Hz. Zaynab to the Valley of Yajaj with his brother Kinana. After the preparations, they set off.
When the polytheists heard about it, they followed them and startled the camel that Hz. Zaynab was riding. She fell off the camel and injured her face. She had a miscarriage due to fear.
Kinana was good at archery. When she saw that Hz. Zaynab fell off, he placed an arrow on the bow, pointed it to the polytheists and said, “I will stick it into your heart if you approach.” The polytheists could not approach. After a while, Abu Sufyan, the leader of Quraysh arrived. He said to Kinana that people would regard it as concession to Muslims if he took Zaynab during the day. He begged Kinana to take Zaynab at night. Kinana accepted it and delivered Zaynab to the two Companions at night.
This small group arrived in Madinah after a difficult and tiring journey. When Hz. Zaynab met her father and siblings, she forgot her pains.
The Prophet appreciated the act of his son-in-law. He praised him by saying, “He talked to me and told me the truth. He promised to me and kept his promise.”
Hz. Zaynab became happy and peaceful in Madinah. Her husband had a troublesome life after he sent Zaynab. Meanwhile, the light of guidance started to enlighten his heart. He considered it for a while and decided to become a Muslim. He collected his receivables from the polytheists and paid his debts. Then, he addressed them as follows: “Do I owe any money to anybody?” When they said he did not owe any money, he declared that he had become a Muslim as follows:
“Then, listen to me very well. I have become a Muslim. I witness that there is no god but Allah. I also witness that Muhammad is His slave and Messenger.”
The polytheists were astounded. They did not know what to do. Abu'l As left them in astonishment and went to Madinah. He went into the presence of the Messenger of Allah and declared that he had become a Muslim.
The Prophet became very happy when he heard it. He praised Abu'l As. He married Zaynab off to him again. This incident took place in the 7th year of the Migration.
Hz. Zaynab had two children called “Umama” and “Ali” but Ali died at a young age. When he got very ill, Hz. Zaynab called her father. The Prophet came to his daughter's house. When he saw that she was very sad, he said, “What Allah gives and takes definitely belong to Him. Everything has a determined period of life.” Then, he took Ali on his lap. Ali was about to die. The Prophet started to cry due to his compassion. When Sa’d bin Ubada saw it, he asked, “O Messenger of Allah! What is this?” The Prophet said, “This is mercy put into the hearts of slaves by Allah. Allah shows mercy only to those who show mercy to others.” Ali died and they buried him.
Zaynab died in the 8th year of the Migration. Her dead body was washed by Umm Ayman. The Prophet took off his sash and gave it to Umm Ayman to use it as a part of her shroud. He led her janazah prayer himself. Then, he went into the grave dug for her thoughtfully and sorrowfully. After staying there for a while, he came out of the grave happily and said,
“I thought of the weakness of Zaynab and prayed to Allah to alleviate the troubles and the heat of the grave for her; and He accepted my prayer.” 
 Tabaqat, 8: 30-34; Usdu’l-Ghaba, 5: 237; Muslim, Fadailu’s-Sahaba: 95; Isaba, 4: 312.