Tafsir of An-Nahl 16:74

{فلا تضربوا لله الأمثال} This is a metaphor for associating partners with God (shirk) and likening Him to others. This is because whoever draws comparisons (amthāl) is likening one state to another and one story to another.

{إن الله يعلم} He knows the essence of what you do and its magnitude. He will punish you for it in proportion to that magnitude, for punishment is measured according to the gravity of the sin.

{وأنتم لا تعلمون} You do not know the essence of it, nor the essence of His punishment. It is this ignorance that has drawn you toward it and emboldened you to commit it; thus, this is the justification for the prohibition against shirk.

It is also possible that the meaning is: Do not draw comparisons for God, for God knows how to draw comparisons, while you do not.

{ضَرَبَ اللَّهُ مَثَلًا عَبْدًا مَّمْلُوكًا لَّا يَقْدِرُ عَلَىٰ شَيْءٍ وَمَن رَّزَقْنَاهُ مِنَّا رِزْقًا حَسَنًا فَهُوَ يُنفِقُ مِنْهُ سِرًّا وَجَهْرًا ۖ هَلْ يَسْتَوُونَ ۚ الْحَمْدُ لِلَّهِ ۚ بَلْ أَكْثَرُهُمْ لَا يَعْلَمُونَ}