"Or do they say, 'He has fabricated it'"—meaning Muhammad has fabricated the Quran: he invented it; that is, they have indeed said that.
"Say, 'Then bring ten surahs like it that have been fabricated, and call upon whomever you can besides Allah'"—meaning: seek the help of those who obey you besides Allah.
﴿أم يَقُولُونَ افتراه﴾ افْتَرَى مُحَمَّدٌ الْقُرْآنَ: اخْتَلَقَهُ؛ أَيْ: قَدْ قَالُوا ذَلِكَ.
﴿قُلْ فَأْتُوا بِعَشْرِ سُوَرٍ مِثْلِهِ مُفْتَرَيَاتٍ وَادْعُوا مَنِ اسْتَطَعْتُمْ مِنْ دُونِ اللَّهِ﴾ أَيِ: اسْتَعِينُوا مَنْ أَطَاعَكُمْ مِنْ دون الله.
