It is narrated from Hazrat Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) freed Hazrat Safiyyah (may Allah be pleased with her), daughter of Huyayy, and made her freedom her dowry.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 12866
Hadith Gradingحکم دارالسلام:إسناده صحيح، خ: 5169، باب فضيلة إعتاقه أمته ثم يتزوجها