Sayyiduna Jabir (may Allah be pleased with him) says: We set out with the Prophet (peace and blessings be upon him) in the state of ihram for Hajj, and he (peace and blessings be upon him) ordered us "to share in camels and cows, seven persons together"; seven of us would share in one camel or cow.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19235