Imam al-Askari (peace be upon him): In hardness, your hearts became like solid rocks or harder than rock. [Allah] states this ambiguously and does not clarify it - like someone who tells another, "I ate bread or meat". He does not mean that he does not know what he ate; rather, he wants to leave the listener uncertain, so that the listener does not know exactly what he ate, though he wants the listener to understand that he ate something regardless. The meaning of the verse is not "rather, harder than rock", because istidrak (stating something incorrectly at first and then correcting it) is itself a kind of error, and it is impossible to attribute to Allah that He would state something incorrectly and then correct Himself, since He has knowledge of the past, the present and the future, and [knows] how anything that comes to exist in the future will be. This kind of correction belongs only to imperfect creatures. Nor does it mean "your hearts are like rock and harder than rock", because [if it said your hearts are hard like rock, then said harder than rock] the second statement would contradict the first, since the first statement says their hearts are equal to rock in hardness, neither harder nor softer than it. And if, after that, the next statement said "rather, harder than rock", it would nullify the previous statement and retract the first statement, since the first statement says their hearts are not harder than rock. This is a parable for one who means to convey that "your hearts are not a source of any good, neither little nor much". In the first clause it is stated ambiguously, since He says "أَوْ أَشَدُّ [or harder]", but in the second clause it is made clear that they are harder than rock. This clarification is not through the words "أَوْ أَشَدُّ قَسْوَةً [or harder in hardness]", but through this [following] verse. They used to say, "O Muhammad (peace be upon him and his family)! You imagine that our hearts have no inclination to support the destitute, help the helpless, and spend money to defeat falsehood and eliminate it, and to aid and revive the truth. In short, [you imagine] there is nothing of human qualities in these hearts, and that these hard rocks are, by far, softer than these hearts and more submissive to Allah's command! Look - here are the mountains before us; let us go near them together and ask them to bear witness to your truthfulness and our falsehood. If they speak and, in eloquent language, confirm you, then you are indeed right and we will necessarily follow you and submit. But if they deny you, or remain silent and give no answer, then know that you have erred in your claim and that you are following the path of stubbornness and hostility out of caprice". The Prophet (peace be upon him and his family) said, "There is no difficulty in that; let us go to whichever of these mountains you wish, so that I may call it to witness, and it will testify in my favour and against you". They set out and chose the hardest rock they could see, and said [to the Prophet, peace be upon him and his family], "Here is the mountain - call it to witness". The Messenger of Allah (peace be upon him and his family) turned to the mountain and said, "O mountain! I ask you, by the greatness of the station of Muhammad (peace be upon him and his family) and the pure ones of his household, for whose sake, when their names were mentioned in respect, Allah accepted the repentance of Adam (peace be upon him) ... and raised Idris (peace be upon him) to a lofty station in Paradise - I ask you to bear, for these Jews, the witness that Allah has entrusted to you, concerning the hardness of their hearts and their denial of what Muhammad, the Messenger of Allah (peace be upon him and his family), has said". The mountain moved, water flowed from it, and it cried out, "O Muhammad (peace be upon him and his family)! I bear witness that you are the Messenger of the Lord of the worlds and the best of all people, and I bear witness that the hearts of these Jews, as you have described, are harder than rock, and nothing comes out of them - just as water gushes forth in a flood or bursts out from the heart of a rock [yet these people's hearts show no such softening] - and I bear witness that they are lying in the false accusation they bring against you, concerning the Lord of the worlds".