Language:
كتاب النكاح
67  
Wedlock, Marriage (Nikaah)
(69)
Chapter: Al-Walima is to be given even with one sheep
(68)
باب الْوَلِيمَةِ وَلَوْ بِشَاةٍ
Sahih al-Bukhari 5168

Narrated Anas:

The Prophet (ﷺ) did not give a better wedding banquet on the occasion of marrying any of his wives than the one he gave on marrying Zainab, and that banquet was with (consisted of) one sheep.

حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا حَمَّادٌ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، قَالَ مَا أَوْلَمَ النَّبِيُّ صلى الله عليه وسلم عَلَى شَىْءٍ مِنْ نِسَائِهِ، مَا أَوْلَمَ عَلَى زَيْنَبَ أَوْلَمَ بِشَاةٍ‏.‏
Reference : Sahih al-Bukhari 5168
In-book reference : Book 67, Hadith 103
USC-MSA web (English) reference : Vol. 7, Book 62, Hadith 97
  (deprecated numbering scheme)