Ever heard the phrase "killing with kindness"?
The history of Hungary at this point is strongly intertwined with the history of the Cumans, an ethnic group of Turkic origins. According to the chronicles, István liked the Cuman tribes and supported them, which put him at odds with most of the Hungarian nobility. When the king got sick with dysentery and was reported to be on his death bed, Hungarians took the opportunity to rise up and slaughter a large number of the Cumans. Their chief, Tatár, went to the king to complain, surrounded by his wailing entourage, recounting the injustice done to his people. István, reportedly, said "Once I am healed, I will kill ten of them in return for each one of your people!" His promise and his kindness made such an impression on the Cumans that they all crowded on him, trying to kiss his hand and hug him at the same time... And they ended up crushing the king so hard he fell ill again and died soon after.
Squeezing people with dysentery is never a good idea.
(At least he knew he was loved in the end.)