الْعِلْمُ نُورٌ، وَلَكِنَّهُ لَا يَنْفَعُ مَنْ لَا يَعْمَلُ بِهِ.
Knowledge is light, but it does not benefit one who does not act upon it.
Through maʿānī the nominal statement puts forward a general claim and the adversative qualification restricts its practical consequences. Through bayān the expressed pair “knowledge/light” is readily analysed as an eloquent simile.
No ornate paronomasia or ordered antithesis need be forced into the passage. The absence of an obvious badīʿ device is not a defect; the value of the analysis lies in how the forms support the argument.