Marriage to Muhammad
Khadija entrusted a friend named Nafisa to approach Muhammad and ask if he would consider marriage. When Muhammad hesitated because he had no money to support a wife, Nafisa asked if he would consider marriage to a woman who had the means to provide for herself. Muhammad agreed to meet with Khadija, and after this meeting they consulted their respective uncles. The uncles agreed to the marriage, and Muhammad's uncles accompanied him to make a formal proposal to Khadija.
It is disputed whether it was Hamza ibn Abdul-Muttalib, Abu Talib, or both who accompanied Muhammad on this errand. Khadija's uncle accepted the proposal, and the marriage took place. At the time of the marriage Muhammad was around 23 to 25 years old. Khadija was 40 years old at that time according to some sources. However, other sources claim that she was aged approximately 28 or 30 during the marriage.
Previous marriages - Shia version
Ibn Shahrashub quoted from al-Sayyid al-Murtada in al-Shafi and al-Shaykh al-Tusi in al-Talkhis, that Khadija was a virgin when she married Muhammad. Considering the cultural and intellectual situation in Hijaz, and the high position and status Khadija al-Kubra enjoyed, among other people, it is improbable that she would have married men from Banu Tamim or Banu Makhzum (the two 'low' tribes). Some believe the two children attributed to Khadija were the children of Hala, Khadija's brothers. After the death of Hala's husband, Khadija took care of Hala and (after Hala's own death) Hala's children
Previous marriages - Sunni version
Khadija married three times and had children from all her marriages. While the order of her marriages is debated, it is generally believed that she first married Atiq ibn 'A'idh ibn' Abdullah Al-Makhzumi, followed by Malik ibn Nabash ibn Zargari ibn at-Tamimi. To Atiq, Khadija bore a daughter named Hindah. This marriage left Khadija a widow. With Malik, she had two daughters, who were named Hala and Hind. Malik also left Khadija a widow, dying before his business became a success. Khadija subsequently proposed to Muhammad.