Surah Hud 11:13

أَمْ يَقُولُونَ ٱفْتَرَىٰهُ ۖ قُلْ فَأْتُوا۟ بِعَشْرِ سُوَرٍ مِّثْلِهِۦ مُفْتَرَيَـٰتٍ وَٱدْعُوا۟ مَنِ ٱسْتَطَعْتُم مِّن دُونِ ٱللَّهِ إِن كُنتُمْ صَـٰدِقِينَ

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

Tafsir

Or do they say ‘He has invented it’? that is the Qur’ān. Say ‘Then bring ten sūras the like thereof in terms of clarity and rhetorical excellence invented for you are Arabs who speak Arabic eloquently like myself — he challenged them to these ten sūras first and then to one sūra — and call in order for them to assist …

Excerpt from Tafsir al-Jalalayn, commentary on 11:13, via Quran.com. The reader has the full commentary and 9 more tafsirs.