Here, Allah (swt) portrays the severity of the scene. We can observe that those in the Hell, with its extreme heat and burning fire, are not given the opportunity to drink except boiling water and pus.

حَمِيمًا (scalding): Extreme heat.

غَسَّاقًا (purulence): Pus excreted from the bodies which are burning in the fire which are extremely disgusting.