إِنَّمَا تَظْهَرُ ثَمَرَتُهُ حِينَ يَنْفَعُ النَّاسَ.
Its fruit becomes apparent when it benefits people.
The first error is overgeneralising a context-bound restriction. The second is classifying every familiar image as an equally strong fresh metaphor, ignoring conventional usage.
The third error is detaching a device from the composition. Restriction, reproach and exclamation take their force from preceding clauses. Analyse word, sentence and whole passage together.