Sahih al-Bukhari, Volume 7, Book 62, Hadith 98 (USC-MSA) ⓘ
Narrated Anas: Allah's Messenger manumitted Safiyya and then married her, and her Mahr was her manumission, and he gave a wedding banquet with Hais (a sort of sweet dish made from butter, cheese and dates).
حَدَّثَنَا مُسَدَّدٌ، عَنْ عَبْدِ الْوَارِثِ، عَنْ شُعَيْبٍ، عَنْ أَنَسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أَعْتَقَ صَفِيَّةَ، وَتَزَوَّجَهَا وَجَعَلَ عِتْقَهَا صَدَاقَهَا، وَأَوْلَمَ عَلَيْهَا بِحَيْسٍ.
also referenced under: Book 67, Hadith 104 (In-Book) & Hadith 5169 (DarusSalam)