Abdullah bin al-Sa'ib, of Banu al-Muttalib, narrates that Sayyiduna Uthman bin Affan (may Allah be pleased with him) married the daughter of al-Furafisah al-Kalbiyyah, who was a Christian, in addition to his (other) wives; then she accepted Islam at his hands.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13981