Yaqub bin Zaid narrated from his father that the Prophet Muhammad (peace be upon him) said: "Arafah is the day in which people recognize (each other)."
Hadith Referenceسنن الدارقطني / كتاب الحج / 2444
Hadith Takhrij«أخرجه الدارقطني فى ((سننه)) برقم: 2444»