Musannaf Ibn Abi Shayba 27:26

Ibn Bishr narrated to us, he said: Ubayd Allah ibn Umar narrated to us, from Nafi, from Ibn Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, before you is a cistern (Hawd) [the distance of which is] like what is between Jarba and Adhruh."