Towards the close of the year 625, the Holy Prophet married Hafsa, and Uthman was married to Umm Kulthum the third daughter of the Holy Prophet. While still a child she was engaged to Utaibah a son of Abu Lahb, an uncle of the Holy Prophet. When the Holy Prophet declared his mission, Abu Lahb opposed him, and under his instructions his son Utaibah repudiated his engagement to Umm Kulthum.
When the Holy Prophet married Umm Kulthum to Uthman, he said to her, "Verily, your husband resembles most among men your forefather Abraham, and your father Muhammad". Ibn Asakir has recorded on the authority of lbn Umar that the Holy Prophet said," I find a resemblance in Uthman to my forefather Abraham".
Uthman's union with Umm Kulthum was as happy as that of the union between Uthman and Ruqayya. Unfortunately such happiness was short lived, and Umm Kulthum died in 630 barely six years after her marriage. Umm Kulthum bore no child. Ruqayya left a son Abdullah, but he died two years after the death of his mother.