Language:
كتاب النكاح
67  
Wedlock, Marriage (Nikaah)
(70)
Chapter: A bigger Walima on marrying some wives than the other wives
(69)
باب مَنْ أَوْلَمَ عَلَى بَعْضِ نِسَائِهِ أَكْثَرَ مِنْ بَعْضٍ
Sahih al-Bukhari 5171

Narrated Thabit:

The marriage of Zainab bint Jahash was mentioned in the presence of Anas and he said, "I did not see the Prophet (ﷺ) giving a better banquet on marrying any of his wives than the one he gave on marrying Zainab. He then gave a banquet with one sheep."

حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ ثَابِتٍ، قَالَ ذُكِرَ تَزْوِيجُ زَيْنَبَ ابْنَةِ جَحْشٍ عِنْدَ أَنَسٍ فَقَالَ مَا رَأَيْتُ النَّبِيَّ صلى الله عليه وسلم أَوْلَمَ عَلَى أَحَدٍ مِنْ نِسَائِهِ مَا أَوْلَمَ عَلَيْهَا أَوْلَمَ بِشَاةٍ‏.‏
Reference : Sahih al-Bukhari 5171
In-book reference : Book 67, Hadith 106
USC-MSA web (English) reference : Vol. 7, Book 62, Hadith 100
  (deprecated numbering scheme)