It was reported that: Ibn As-Sammaak entered upon Haroon Ar-Rasheed (the Abbasid Caliph) one day, and while he was with him, Ar-Rasheed asked (his attendants) for some water. Someone brought him a cup of water, and when he was about to drink from it, Ibn As-Sammaak said to him, ‘Oh Ameer-ul-Momineen (Leader of the Muslims), please wait, I ask you by your nearness to the Messenger of Allah ﷺ, if you were prevented from drinking this water (because of an ailment), how much would you be willing to pay for it?’ He replied, ‘With half of my kingdom.’ Ibn As-Sammaak said, ‘Then drink, may Allah bless it.’ After he drank, Ibn As-Sammaak asked him, ‘I ask you by your nearness to the Messenger of Allah ﷺ, if you were prevented from excreting it out of your body, how much would you be willing to pay for it (to cure that condition)?’ Haroon Ar-Rasheed replied, ‘With all of my kingdom.’ Ibn As-Sammaak said, ‘A kingdom whose worth is (only) a sip of water is not worth competing for.’ Haroon Ar-Rasheed cried at this.
From Tareekh At-Tabari. (Translated by Mohammed Manna.)
With this short Naseehah (advice), Imam Ibn As-Sammaak wanted to remind the Caliph Haroon Ar-Rasheed about the fleeting nature of this world, and that he should always remember that the Akhirah (the afterlife) is the main purpose of our existence and not these kingdoms that are pettier than a small bowl of water.
Saheehus-Seerah 