The word(s) "hardened" appears 4 time(s) in 4 verse(s) in Quran in Saheeh International translation.

(1) Then your hearts became hardened after that, being like stones or even harder. For indeed, there are stones from which rivers burst forth, and there are some of them that split open and water comes out, and there are some of them that fall down for fear of Allah. And Allah is not unaware of what you do.

(2) Then why, when Our punishment came to them, did they not humble themselves? But their hearts became hardened, and Satan made attractive to them that which they were doing.

(3) So is one whose breast Allah has expanded to [accept] Islam and he is upon a light from his Lord [like one whose heart rejects it]? Then woe to those whose hearts are hardened against the remembrance of Allah. Those are in manifest error.

(4) Has the time not come for those who have believed that their hearts should become humbly submissive at the remembrance of Allah and what has come down of the truth? And let them not be like those who were given the Scripture before, and a long period passed over them, so their hearts hardened; and many of them are defiantly disobedient.