Musnad Ahmad 27:1619

Yunus narrated to us, Hammad—meaning Ibn Zayd—narrated to us, from Ayyub, 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 basin (Hawd), the distance between its two sides is as the distance between Jarba’ and Adhruh."