Sahih Muslim Book 004, Hadith Number 1015.
Chapter : The excellence of the prayer and the way it is begun and the excellence of Ruku' and moderation in it and prostration and moderation in it, etc.
Abu Juhaifa reported on the authority of his father: I saw the Messenger of Allah (may peace be upon him) (in Mecca at al-Abtah) in a red leather tent and I saw Bilal take the ablution water (left by Allah's Messenger), and I saw the people racing, with one another to get that ablution water. If anyone got some of it, he rubbed himself with it, and anyone who did not get any got some of the moisture from his companion's hand. I then saw Bilal take a staff and fix it in the ground, after which the Messenger of Allah (may peace be upon him) came out quickly in a red mantle and led the people in two rak'ahs facing the staff, and I saw people and animals passing in front of the staff.