Al-Walima is to be given even with 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.
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.