Machine summary:
Just as the Prophet (PBUH) said to Ali (AS) regarding the marriage of his daughter Hazrat Zahra (SA): One of the important matters that holds great significance in human life and upon which the future of humans and their children depends is the matter of marriage, which must always be carefully considered and calculated.
The Marriage of the Prophet to Khadija When Hazrat Muhammad (PBUH) went with his uncle Abu Talib (AS) to propose to Khadija al-Kubra, His Eminence had neither a house, nor money, nor possessions; however, after Khadija accepted the blessed matter of marriage to the Prophet, Abu Talib, in the marriage sermon, mainly referred to spiritual matters, the honor and value of his brother's son, Hazrat Muhammad (PBUH), and similar things, especially the nobility, lineage, status, and position of Hazrat Muhammad, which reveals the meaning of being compatible and well-matched.
And here is the marriage of the Prophet to Khadija (SA) from the words of Imam Sadiq (AS), who says: «When Muhammad (PBUH) decided to marry Khadija, the daughter of Khuwailid, Abu Talib, with his family and a group from the Quraysh, went to the house of Waraqa bin Nawfal, the uncle of Khadija.
The reason and cause of Khadija's interest in marrying Muhammad (PBUH) Hazrat Khadija (SA), that virtuous and pious lady of noble and deep-rooted lineage, who was intelligent and possessed wealth and trade, and whose marriage the leaders of the Quraysh were always seeking but to whom they had all given negative responses; when Muhammad (PBUH) went with his uncle to propose, she not only gave a positive response but also took the responsibility of the dowry herself.