Overall meaning : Allah, Exalted be He, says to His Prophet, Muhammad, may Allah bless him and grant him peace, that He knows full well that what his unbelieving people say grieves him. He should not, therefore, think, He reassures him, that they say so because they doubt his honesty and the truthfulness of his message, for they know in the heart of their hearts that he is truthful and the message he has brought them is the truth, but these unbelievers, out of sheer obstinacy due to their wrongdoing, deny the signs and proofs that are the truth from Allah.
Still consoling His Prophet, may Allah bless him and grant him peace, He exhorts him to follow the example of the messengers before him, stating that they were also denied and rejected but they continued conveying Allah’s message, meeting their people’s denial and the harm they suffered with patience, until His help and support came to them. He affirms that none can possibly change Hs words pertaining to His promise to His Messenger, Muhammad, may Allah bless him and grant him peace, to aid him and those with him and grant them victory, and informs him that he has already received accounts of messengers before him who received His aid and carried the day in the end.
Next, He informs His Prophet, may Allah bless him and grant him peace, that he has no choice but to arm himself with patience and perseverance: If you find your unbelieving people’s aversion hard to bear, then if you are able to go down a tunnel deep into the earth or ascend a ladder to the sky to bring them a yet more convincing sign, do so if you can, as this will not avail them at all. Had Allah so willed, He would indeed have guided them all to the right path. Then He enjoins him not to be of those who are ignorant of His ways in His creation and who do not comprehend the truth of things; otherwise, their aversion will be even more distressing for him and he will be saddened tremendously by their unbelief.