Muwatta Malik, Book 23, Hadith 1040 (In-Book) ⓘ

Yahya related to me from Malik from Umara ibn Yasar that Ata ibn Yasar told him that Abu Ayyub al-Ansari had told him, "We used to sacrifice one sheep, and a man sacrificed for himself and his family. Then later on people began to compete with each other and it became boasting." Malik said, "The best that I have heard about a single camel, cow or sheep, is that a man should sacrifice a camel for himself and his family. He sacrifices a cow or sheep which he owns for his family, and shares with them in it. It is disapproved for a group of people to buy a camel, cow or sheep, to share for the ritual and sacrifices, each man giving a share of its price, and taking a share of its meat. We have heard the tradition that people do not share in the ritual. However, it may be that the people of one household can share."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ عُمَارَةَ بْنِ صَيَّادٍ، أَنَّ عَطَاءَ بْنَ يَسَارٍ، أَخْبَرَهُ أَنَّ أَبَا أَيُّوبَ الأَنْصَارِيَّ أَخْبَرَهُ قَالَ كُنَّا نُضَحِّي بِالشَّاةِ الْوَاحِدَةِ يَذْبَحُهَا الرَّجُلُ عَنْهُ وَعَنْ أَهْلِ بَيْتِهِ ثُمَّ تَبَاهَى النَّاسُ بَعْدُ فَصَارَتْ مُبَاهَاةً ‏.‏