"Or do they say," meaning: that Muhammad has forged the Quran, in the form of an inquiry; meaning: they have indeed said it. Allah, Glorified and Exalted is He, said: "O Muhammad, say: 'Then bring a surah like it,'" like this Quran, "and call upon," meaning: seek assistance from, "whomever you can," meaning: whoever obeys you, "besides Allah, if you should be truthful," meaning: you are not truthful, and you will not bring a surah like it.