قَالَ رَبِّىٓ أَعْلَمُ بِمَا تَعْمَلُونَ
Commentary:
Prophets of God are great lovers of mankind. Their hearts are full of the milk of human kindness. The people of Shu‘aib challenged him to bring down Divine punishment on them if indeed he was a true Messenger of God. To this insolent challenge Shu‘aib replied that his knowledge being imperfect it was not for him to decide if and when the punishment should and would overtake them and that it was God, their Lord and Creator, Who being fully acquainted with the nature of their deeds knew whether or not they had rendered themselves deserving of the punishment they demanded. In fact, God has reserved to Himself the right when and whom to punish and whom to spare. If it had been left to the Prophets to decide who was deserving of punishment, many prospective believers would have died as disbelievers.
To the insolent challenge of his people to bring down punishment upon them, (Kisaf meaning, Divine punishment), Shu‘aib replied that his knowledge being imperfect it was not for him to decide if and when the punishment should and would overtake them and that it was God, their Lord and Creator, Who being fully acquainted with the nature of their deeds, knew whether or not they had rendered themselves deserving of the punishment they demanded.