﴿ سَأُرْهِقُهُۥ صَعُودًا ﴾

“[and so] I shall constrain him to endure a painful uphill climb!”

(On him I shall impose a fearful doom) I shall make him climb a smooth rock in the Fire such that whenever he puts his hands on it, he wwould melt, and then he will be restored to how he used to be; it is also said that Allah will make him climb a rock of copper which pulls him from the front and hits him from the back.