Sayyiduna Abu Hurairah, may Allah be pleased with him, narrated that the Truthful and Trusted (the Prophet), peace and blessings be upon him, told us: "On the Day of Resurrection, the very first case to be decided will be between two goats: one with horns and the other without horns."
Hadith Referenceمسند اسحاق بن راهويه / كتاب أحوال الاخرة / 949