Abu Ishaq narrates from Harithah bin Wahb (may Allah be pleased with him) that he said: I prayed with the Prophet (peace and blessings be upon him) at Mina, and the people were very many; he (peace and blessings be upon him) led two rak'ahs during the Farewell Hajj.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5381