Abu Hurairah (May Allah be pleased with him) said:
The Messenger of Allah (ﷺ) said, "Saihan (Oxus), Jaihan (Jaxartes), Al-Furat (Euphrates) and An-Nil (Nile) are all from the rivers of Jannah."[Muslim]. (JA)
App reference (JA): Book 19, Hadith 46 (JA)
Arabic/English book reference (JA): Book 19, Hadith 1853 (JA)