﴿ ۞ إِنَّ ٱللَّهَ لَا يَسْتَحْىِۦٓ أَن يَضْرِبَ مَثَلًۭا مَّا بَعُوضَةًۭ فَمَا فَوْقَهَا ۚ فَأَمَّا ٱلَّذِينَ ءَامَنُوا۟ فَيَعْلَمُونَ أَنَّهُ ٱلْحَقُّ مِن رَّبِّهِمْ ۖ وَأَمَّا ٱلَّذِينَ كَفَرُوا۟ فَيَقُولُونَ مَاذَآ أَرَادَ ٱللَّهُ بِهَٰذَا مَثَلًۭا ۘ يُضِلُّ بِهِۦ كَثِيرًۭا وَيَهْدِى بِهِۦ كَثِيرًۭا ۚ وَمَا يُضِلُّ بِهِۦٓ إِلَّا ٱلْفَٰسِقِينَ ﴾

“Behold, God does not disdain to propound a parable of a gnat, or of something [even] less than that. Now, as for those who have attained to faith, they know that it is the truth from their Sustainer - whereas those who are bent on denying the truth say, "What could God mean by this parable?" In this way does He cause many a one to go astray, just as He guides many a one aright: but none does He cause thereby to go astray save the iniquitous,”

Please check ayah 2:27 for complete tafsir.