Sisyphus, king of Ephyra, ruled over this kingdom using navigation and commercial hub, but was very deceitful and violated the Xenia law which Zeus instituted.
Following the Xenia meant to show hospitality and generosity, so violating it meant to kill others to prove you are ruthless in your acts.
I will kill you and show you my wrath. Never mess with me!!
Please no! Don't do this!
Sisyphus has finally angered me. I will send you, Thanatos, to grab Sisyphus and send him to the underworld
As Thanatos got hold of Sisyphus, Sisyphus was able to trick Thanatos and chain him with his own equipment. After trapping him, Sisyphus got away and was able to get free.
How dare you! You will pay for this!
Because Sisyphus blocked the passage of the Underworld, it meant that the living could not pass to the realm of the dead. This angered Ares, the god of war because it meant that his challenges meant nothing, for no one would die.
So, Ares had decided to grab Sisyphus himself and throw him into the Underworld.
Sisyphus, now stripped of everything he had, was punished by Zeus for eternity to push a boulder up a mountain, although every time he made it to the top, the rock would roll back down and he would have to carry it back up again.