Musannaf Ibn Abi Shayba 30:150

Muhammad ibn Bishr narrated to us, he said: Sa'id ibn Abi 'Aruba narrated to us, from Qatada, from Salim ibn Abi al-Ja'd, from Ma'dan ibn Abi Talha al-Ya'mari, from Thawban, that the Prophet, peace and blessings of Allah be upon him, was asked about the width of the Basin (al-Hawd). He said: "The distance between my station here and 'Uman; the distance between them is a month, or something like that." Then the Messenger of Allah, peace and blessings of Allah be upon him, was asked about its drink. He said: "Whiter than milk and sweeter than honey. Two spouts pour into it, their supply—or their supply—is from Paradise; one of them is of silver and the other is of gold."