Waki' bin al-Jarrah وكيع بن الجراح · Chapters on the description of Paradise

"What is Al-Kawthar?" He said: "That is a river that Allah has given me"- that is, in Paradise- 'whiter than milk and sweeter than honey. In it are birds whose necks are like the necks of camels." 'Umar said: "Indeed this is plump and luxurious then." So the Messenger of Allah (s.a.w) said, "Those who consume it are more plumb than it."