Musnad Abu Ya'la al-Mawsili 145:1

Ghassan ibn al-Rabi' narrated to us, from Hammad ibn Salamah, from Shu'ayb ibn al-Habhab and 'Abd al-'Aziz ibn Suhayb, from Anas ibn Malik: That the Prophet (ﷺ) emancipated Safiyyah and made her emancipation her dowry.