Sahih Bukhari Volume 002, Book 026, Hadith Number 715.
Narated By 'Abdul 'Aziz bin Rufai : I asked Anas bin Malik, "Tell me what you remember from Allah's Apostle (regarding these questions): Where did he offer the Zuhr and 'Asr prayers on the day of Tarwiya (8th day of Dhul-Hajja)?" He relied, "(He offered these prayers) at Mina." I asked, "Where did he offer the 'Asr prayer on the day of Nafr (i.e. departure from Mina on the 12th or 13th of Dhul-Hijja)?" He replied, "At Al-Abtah," and then added, "You should do as your chiefs do."