“Indeed, my Lord is upon a straight path”: that is, although my Lord has power over them, He does not wrong them and does nothing except with beneficence and justice. Thus, He rewards the one who does good for his goodness and recompenses the evildoer for his disobedience.
It was also said that it means: the religion of my Lord is upon a straight path.
It was also said (1) that an implied meaning is understood here: that is, my Lord urges you and directs you toward a straight path.
“If you turn away, then I have conveyed to you that with which I was sent to you. My Lord will replace you with another people, and you will not harm Him in the least. Indeed, my Lord is Guardian over all things. (57) When Our command came, We saved Hud and those who believed with him by a mercy from Us, and We saved them from a severe punishment. (58) Such was ‘Ad: they rejected the signs of their Lord, disobeyed His messengers, and followed the command of every arrogant, obstinate tyrant. (59) They were pursued by a curse in this world and on the Day of Resurrection. Indeed, ‘Ad disbelieved in their Lord. Away with ‘Ad, the people of Hud! (60)”
“If you turn away”: that is, if you turn away—meaning, if you turn aside from that to which I have called you—“then I have conveyed to you that with which I was sent to you. My Lord will replace you with another people”: that is, if you turn away, Allah, exalted is He, will destroy you and replace you with another people more obedient than you, who affirm His oneness and worship Him. “And you will not harm Him in the least” through your turning away and refusal; rather, you only harm yourselves.
It was also said that it means: you will not diminish Him in the least if He destroys you, for your existence and your nonexistence are the same to Him. “Indeed, my Lord is Guardian over all things”: that is, He preserves all things and protects me from your harming me.
Concerning His saying, “When Our command came”: that is, Our punishment. “We saved Hud and those who believed with him”; they numbered four thousand. “By a mercy from Us”: that is, by a favor from Us. “And We saved them from a severe punishment”: this was the wind by which He destroyed ‘Ad. It was also said that the severe punishment refers to the punishment on the Day of Resurrection; that is, just as We saved them from punishment in this world, so too We saved them in the Hereafter.
“Such was ‘Ad”: the pronoun refers back to the tribe. “They rejected the signs of their Lord and disobeyed His messengers”: that is, Hud alone. He is mentioned in the plural because whoever denies one messenger is like one who denies all the messengers. “And they followed the command of every arrogant, obstinate tyrant”: that is, the lowly and base followed those characterized by arrogance and stubborn opposition. A tyrant is one who is arrogant, and an obstinate person is one who does not accept the truth. It is said: a man acts obstinately when he refuses to accept something even though he knows it. Abu ‘Ubaydah said (2): “An obstinate opponent, one who is stubborn, and one who contends are all terms for someone who opposes you through disagreement.”
“They were pursued by a curse in this world”: that is, they were followed by a curse that clung to them and accompanied them. A curse is banishment and expulsion from mercy. “And on the Day of Resurrection”: that is, they were cursed on the Day of Resurrection as well; indeed, they were cursed in this world and the Hereafter.