The word(s) "harder" appears 2 time(s) in 2 verse(s) in Quran in Mohsin Khan translation.

(1) For them is a torment in the life of this world, and certainly, harder is the torment of the Hereafter. And they have no Waq (defender or protector) against Allah.

(2) "Or some created thing that is yet greater (or harder) in your breasts (thoughts to be resurrected, even then you shall be resurrected)." Then, they will say: "Who shall bring us back (to life)?" Say: "He Who created you first!" Then, they will shake their heads at you and say: "When will that be?" Say: "Perhaps it is near!"