Overall meaning : Say, O Muhammad: Am I to take other than Allah as my helper and supporter, when He is the Originator of the heavens and the earth, the Self-Sufficient who is absolutely independent of the whole creation, who provides for all His creatures and does not stand at all in need of them?!
Say, O Muhammad: I have been commanded by my Lord to be the first to surrender to Him, and not to be of those who ascribe partners to Him and worship them besides Him.
Say, O Muhammad: I fear that if I disobey my Lord I will suffer the punishment of the awfully dreadful Day of Judgement. Whoever is spared torment on that day will surely have received Allah’s grace and mercy. That will surely be clear salvation and real success.