Al-Matalib al-'Aliyah 4614 — The description of Paradise

It is narrated from Abu al-Khayr (may Allah have mercy on him) that Ka'b al-Ahbar (may Allah have mercy on him) said: "The river Nile is the river of honey in Paradise, the river Tigris is the river of milk in Paradise, the river Euphrates is the river of wine in Paradise, and the river Sayhan is the river of (pure, clear) water in Paradise." He further said: "Then Allah Almighty concealed their (special, Paradise) light and splendour (in the world) so that they may be made part of Paradise again (on the Day of Resurrection)."
Imam al-Harith bin Abi Usamah recorded this report in his Musnad (Bughyat al-Bahith: 4614); its narrators are thiqat (trustworthy), and it is a saying of Ka'b al-Ahbar (mawquf).