She was the daughter of Hayi, Who was a descendant of Hadhrat Harun (a.s) the brother of Moosa (a.s). She was first married to Salam bin Mishkam and then to Kinallah bin Abi Huqaiq at the time of Khevbar. Kinallah was killed in the battle and she was captured by the Muslims. Hadhrat Dahya Kalbi (Radhiyallaho anha) requested for a maid, and the Prophet Mohammad (SAW) made her over to him. At this, the other Sahabah approached the Prophet Mohammad (SAW) and said:
“O, Prophet of Allah! Banu Nazir and Banu Quraizah (the Jewish tribes of Madinah) will feel offended to see the daughter of a Jewish chief working as a maid. We therefore suggest that she may be taken as your own wife.”
The Prophet Mohammad (SAW) paid a reasonable sum of money to Hadhrat Dahya (r.a) as ransom, and said to Safiyyah: “You are now free; if you like you can go back to your tribe or can be my wife.”
She said: “I longed to be with you while I was a Jew. How can I leave you now, when I am a Muslim.
This is probably a reference to the fact that she once saw in her dream a portion of the moon falling into her lap. When she mentioned her dream to Kinanah, he smote her face so severely that she developed a mark on her eye. He said: “You seem to be desiring to become the wife of the King of Madinah.”
Her father is also reported to have treated her similarly when she related the same or similar dream to him. She again saw (in her dream) the sun lying on her breast. When she mentioned this to her husband, he remarked:
“You seem to be wishing to become the Queen of Madinah.”
She says: “I was seventeen when I was married to the Prophet Mohammad (SAW). She came to live with the Prophet Mohammad (SAW) when he was camping at the first stage from Khaiber. Next morning, he said to the Sahabah: “Let everybody bring whatever he has got to eat.”
They brought their own dates, cheese, butter, etc. A long leather sheet was spread and all sat round it to share the food among themselves. This was the Walimah for the marriage.
She died in Ramadan 50 A. H., when she was about 60.
Source : eislam