It was narrated from Anas that :
the Prophet (ﷺ) bought Safiyyah for seven slaves. (Sahih) (One of the narrators) 'Abdur-Rahman said: "From Dihyah Kalbi.' (ES)
English reference (ES): Vol. 3, Book 12, Hadith 2272 (ES)
Arabic reference (ES): Book 12, Hadith 2358 (ES)