What is the religious ruling on attempting to produce a surah like the Qur’an, knowing that this attempt was merely a fleeting thought and failed, and its author regretted it and sought Allah’s forgiveness?

Opposing the Quran is disbelief and a denial of Allah’s Almighty words: "Say, 'If mankind and the jinn gathered in order to produce the like of this Qur'an, they could not produce the like of it, even if they were to each other assistants.'" and His saying: "And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a surah the like thereof and call upon your witnesses other than Allah, if you should be truthful. But if you do not do it - and you will never do it - then fear the Fire, whose fuel is men and stones, prepared for the disbelievers." If the attempt was merely a fleeting thought that did not settle in the heart, and then you stopped and sought Allah's forgiveness, then there is nothing upon you.