Harun al-Rashid, one of the richest of the Abbasid Caliphs, once heard of a righteous scholar named Ibn As-Sammaak and requested his presence in his chamber to give him good counsel. When the scholar arrived, the Caliph had ordered a glass of water to drink.
Seeing this, Ibn Samaak asked; “what would you give if no water was available to you and you were forced to trade for this one cup of water?”
Harun al-Rashid replied, “I would give at the very least half of my kingdom”
The scholar then asked, “and what would you give if you were unable to release the waste of that water from your body?”
The Caliph said, “I would give the other half of my kingdom”
The Sheikh smiled and told the Caliph, “What value is your kingdom if it can be bought with a glass of water”.