Musnad Abu Ya'la al-Mawsili 115:345

Muhammad ibn Mahdi narrated to us, Abd al-Razzaq narrated to us, Ma'mar informed us, from Qatadah, regarding the saying of Allah: "At the Lote Tree of the Utmost Boundary" (al-Najm). He said: Anas ibn Malik informed me that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The Lote Tree of the Utmost Boundary was raised up for me in the seventh heaven. Its fruits were like the jars of Hajar, and its leaves were like the ears of elephants. From its trunk emerge two manifest rivers and two hidden rivers. I said: 'O Gabriel, what is this?' He said: 'As for the two hidden rivers, they are in Paradise, and as for the two manifest ones, they are the Nile and the Euphrates.'"