Zainab bint Muhammad (Arabic: زَيْنَب بِنْت مُحَمَّد)‎ (598/599–629 CE) was the eldest daughter of the Islamic prophet Muhammad by his first wife Khadijah.

She married her maternal cousin, Abu al-As ibn al-Rabi', before December 610,^{[3]: 313–314 [4]: 21 [5]: 162} and Khadija gave her a wedding present of an onyx necklace.^[4]: 22 They had two children, son Ali, who died in childhood, and daughter Umamah, who would bear children, including Hilal or Muhammad al-Awsat.^{[4]: 21 [5]: 162 [6]} Zainab became a Muslim soon after Muhammad first declared himself a prophet. The Quraysh pressured Abu al-As to divorce Zainab, saying they would give him any woman he liked in exchange, but Abu al-As said that he did not want any other woman, a stance for which Muhammad commended him. Muhammad had no jurisdiction over Mecca and therefore could not force them to separate, so they continued to live together despite Abu al-As's refusal to convert to Islam. Zainab remained in Mecca when the other Muslims following Muhammad migrated to Medina.

Abu al-As was one of the polytheists who was captured at the Battle of Badr. Zainab sent the money for his ransom, including the onyx necklace. When Muhammad saw the necklace, he refused to accept any cash ransom for his son-in-law. He sent Abu al-As home, and Abu al-As promised to send Zainab to Medina.^{[3]: 314 [4]: 22}

Zainab accepted this instruction. About a month after the battle, Zainab's adopted brother, Zayd, arrived in Mecca to escort her to Medina. She entered a hawdaj and her brother-in-law, Kinana, led the camel to Zayd in broad daylight. The Quraysh perceived this as an unnecessary flaunting of Muhammad's triumph at Badr. A group of them pursued Zainab and overtook her at Dhu Tuwa. A man named Habbar ibn Al-Aswad threatened her with his lance^{[3]: 314–315} and pushed her. She fell out of the hawdaj onto a rock.^[5]: 4 Kinana showed the arrows in his quiver and threatened to kill anyone who came any closer. Then Abu Sufyan arrived, telling Kinana to put away his bow so that they could discuss it rationally. He said that they had no intention of keeping a woman from her father in revenge for Badr, but that it was wrong of Kinana to humiliate the Quraysh further by parading her removal in public; he must do it quietly, when the "chatter" had died down. Kinana took Zainab home again. There she suffered a miscarriage, losing a great deal of blood, which she attributed to having been assaulted by Habbar.^{[3]: 314–315}

A few nights later, Kinana took her quietly to meet Zayd, and he escorted her to Medina.^[3]: 315 Anas ibn Malik recalled seeing Zainab in Medina wearing a striped silk cloak.^[4]: 24

Their reconciliation was short-lived, for Zainab died in May or June 629. Her death was attributed to complications from the miscarriage that she had suffered in 624.^[5]: 4 The women who washed her dead body included Umm Ayman, Sawdah and Umm Salama.^[4]: 24

• Muhammad in Islam
• Children of Muhammad
• Genealogy of Khadijah's daughters
• Sahabah