It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "In sacrifices, a camel (suffices) for seven people and a cow (suffices) for seven people."
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from Mughirah except Hafs bin Jumay', and Umar bin Yahya is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 6128
Hadith Takhrij«أخرجه البزار فى «مسنده» برقم: 1563، والطحاوي فى «شرح معاني الآثار» برقم: 6219، والطبراني فى «الكبير» برقم: 10026، والطبراني فى «الصغير» برقم: 862»