Zayd bin Arqam (may Allah be pleased with him) said that the Companions asked the Prophet (peace and blessings be upon him) about these sacrifices, and he (peace and blessings be upon him) said: "It is the sunnah of your father Ibrahim (peace be upon him)." The Companions asked: What reward will we receive in the Hereafter? He (peace and blessings be upon him) said: "For every drop of blood, a good deed."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19016