كتاب الحج
15
The Book of Pilgrimage
(62)
Chapter: It is permissible to share in the sacrifice, and a camel or a cow is sufficient for seven people
(62)
باب الاِشْتِرَاكِ فِي الْهَدْىِ وَإِجْزَاءِ الْبَقَرَةِ وَالْبَدَنَةِ كُلٍّ مِنْهُمَا عَنْ سَبْعَةٍ ‏‏

Jabir b. 'Abdullah (Allah be pleased with him) reported:

In the year of Hudaibiya (6 H ), we, along with Allah's Messenger (way peace be upon him), sacrificed a camel for seven persons and a cow for seven persons.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا مَالِكٌ، ح وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، - وَاللَّفْظُ لَهُ - قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ أَبِي الزُّبَيْرِ عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ قَالَ نَحَرْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم عَامَ الْحُدَيْبِيَةِ الْبَدَنَةَ عَنْ سَبْعَةٍ وَالْبَقَرَةَ عَنْ سَبْعَةٍ ‏.‏
Reference : Sahih Muslim 1318 a
In-book reference : Book 15, Hadith 389
USC-MSA web (English) reference : Book 7, Hadith 3024
  (deprecated numbering scheme)