It was narrated from Abu Hurairah:
that the Messenger of Allah said: 'The wedding feast on the first day is an obligation, on the second day is a custom and on the third day is showing off." (RU)
English reference (RU): Vol. 3, Book 9, Hadith 1915 (RU)
Arabic reference (RU): Book 9, Hadith 1990 (RU)