أَمۡ يَقُولُونَ ٱفۡتَرَىٰهُۖ قُلۡ فَأۡتُواْ بِعَشۡرِ سُوَرٖ مِّثۡلِهِۦ مُفۡتَرَيَٰتٖ وَٱدۡعُواْ مَنِ ٱسۡتَطَعۡتُم مِّن دُونِ ٱللَّهِ إِن كُنتُمۡ صَٰدِقِينَ ١٣
Or do they say, "He invented it"? Say, "Then bring ten sūrahs like it that have been invented and call upon [for assistance] whomever you can besides Allāh, if you should be truthful."
Translation: Saheeh International (English)
Each word's meaning and sound
Do the idolaters say that Muhammad made up the Qur’ān, and that it is not revelation from Allah? Allah tells the Messenger (peace and blessing be upon him) to challenge them to write ten similar sūrahs themselves like the Qur’ān, and to call upon whomever they could call upon to help them to do this, if they were telling the truth in claiming that the Qur’ān was fabricated.
Al-Mukhtasar in interpreting the Noble Quran