Musnad Abu Ya'la al-Mawsili 53:1

Abu Bakr ibn Abi Shaybah narrated to us, Abu Bakr ibn Ayyash and Abu al-Ahwas narrated to us, from Abu Ishaq, from Harithah ibn Wahb, who said: I prayed with the Messenger of Allah (peace and blessings of Allah be upon him) at Mina, when the people were at their most secure and most numerous, [consisting of] two rak'ahs.