Tafsir of As-Saffat 37:91

{فَرَاغَ إِلَىٰ آلِهَتِهِمْ} He turned aside to their gods, meaning he went to them in secret, derived from the "rogha" (cunning/evasion) of a fox.

{آلِهَتِهِمْ} To their idols, which they claimed were gods, similar to the Almighty’s saying: "Where are My partners?"

{أَلَا تَأْكُلُونَ * مَا لَكُمْ لَا تَنطِقُونَ} A mockery of them and their inferiority compared to the state of their worshippers.

{فَرَاغَ عَلَيْهِمْ} He turned upon them secretly. It is as if he said: "He struck them."

{ضَرْبًا} Because "ragha 'alayhim" carries the meaning of striking them. Or, "he turned upon them, striking them a blow." Or, "he turned upon them, striking," meaning "as a striker." It has also been recited as "safqan" and "safqan," both of which mean striking.

{بِالْيَمِينِ} A severe, powerful blow; because the right hand is the stronger and more potent of the two limbs. It is also said: it means with strength and firmness. It is also said: it refers to his oath, which is His saying: "By Allah, I will surely plot against your idols."