Surah Al-Ahqaf 46:11

وَقَالَ ٱلَّذِينَ كَفَرُوا۟ لِلَّذِينَ ءَامَنُوا۟ لَوْ كَانَ خَيْرًا مَّا سَبَقُونَآ إِلَيْهِ ۚ وَإِذْ لَمْ يَهْتَدُوا۟ بِهِۦ فَسَيَقُولُونَ هَـٰذَآ إِفْكٌ قَدِيمٌ

And those who disbelieve say of those who believe, "If it had [truly] been good, they would not have preceded us to it." And when they are not guided by it, they will say, "This is an ancient falsehood."

Translation: Saheeh International

Tafsir

And those who disbelieve say of those who believe that is they say with regards to them ‘Had it faith been anything good they would not have attained it before us’. And since they the ones now speaking will not be guided by it that is by the Qur’ān they say ‘This that is the Qur’ān is an ancient lie!’

Excerpt from Tafsir al-Jalalayn, commentary on 46:11, via Quran.com. The reader has the full commentary and 9 more tafsirs.