It was narrated that Anas bin Malik said:
"I never saw the Messenger of Allah give a wedding feast for any of his wives like the feast he gave for Zainab, for which he slaughtered a sheep." (ID)
English reference (ID): Vol. 3, Book 9, Hadith 1908 (ID)
Arabic reference (ID): Book 9, Hadith 1983 (ID)