From Sahih Muslim (Hadith 3498):
This hadith has been narrated through another chain of transmitters on the authority of Anas that Allah's Apostle (ﷺ) emancipated Safiyya, and her emancipation was treated as her wedding gift, and in the hadith transmitted by Mu'adh on the authority of his father (the words are):" He (the Holy Prophet) married Safiyya and bestowed her emancipation as her wedding gift
Reference: Muslim 3498