Musannaf Ibn Abi Shayba 27:34

Muhammad bin Bishr narrated to us, from Sa’id, from Qatadah, from Salim bin Abi al-Ja’d, from Ma’dan bin Abi Talhah al-Ya’muri, from Thawban, the freed slave of the Messenger of Allah (may Allah bless him and grant him peace), that the Prophet (may Allah bless him and grant him peace) said: "I will be at the side of my cistern, driving the people away from it for the people of Yemen. I will strike them with my staff until it flows for them." He said: The Prophet of Allah (may Allah bless him and grant him peace) was asked about the width of the cistern, and he said: "It is [the distance] between this station of mine and Amman; the distance between them is a month or thereabouts." He was then asked about its drink, and he said: "It is whiter than milk and sweeter than honey. Two spouts pour into it, their supply—or their flow—is from Paradise; one of them is of silver and the other is of gold."