Umme Kulsoom Bint Muhammad was the third daughter of Holy Prophet Muhammad (PBUH) and Hazrat Khadija (R.A). She was born in 600 CE.
When she came of age like her elder sister, she was also married to one of the sons of Abu Lahab. However, after Islam she was also divorced and lived with Prophet (PBUH) in Madina. After the death of her elder sister, Ruqqayah who was married to Hazrat Usman (R.A), Prophet (PBUH) married her to Hazrat Usman (R.A) making him His son in law for the second time.
