The Messenger of Allah ﷺ was asked, "What is al-Kawthar?"He replied, "It is a river that Allah has given me in Paradise. Its water is whiter than milk and sweeter than honey, and in it are birds whose necks are like the necks of camels."Umar remarked, "Those birds must be plump and tender!"The Messenger of Allah ﷺ said, "Those who eat them are even better off than they are."
سئل رسول الله ﷺ ما الكوثر؟ قال: ذاك نهر أعطانيه الله- يعني في الجنة- أشد بياضا من اللبن، وأحلى من العسل، فيه طير أعناقها كأعناق الجزر قال عمر: إن هذه لناعمة! قال رسول الله ﷺ: أكلتها أحسن منها.
Tirmidhi (2542) narrated it from Abd bin Humayd, who reported to us from Abdullah bin Maslama, from Muhammad bin Abdullah bin Muslim, from his father, from Anas bin Malik, and he related it. Its chain is hasan because of Muhammad bin Abdullah bin Muslim, for he is hasan al-hadith. The discussion of this is set out at length in the Book of Iman.