Narrated Abu Bishr:
Sa`id bin Jubair said that Ibn `Abbas said about Al-Kauthar. "That is the good which Allah has bestowed upon His Apostle." I said to Sa`id bin Jubair. "But the people claim that it is a river in Paradise." Sa`id said, "The river in Paradise is part of the good which Allah has bestowed on His Apostle." (DE)
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 490 (DE)
Arabic reference (DE): Book 65, Hadith 4966 (DE)