Overall meaning : The Almighty says: Recite, Muhammad, what Allah has revealed to you of the Qur’an, convey it to people and follow its teachings. None can change Allah’s Words which He has revealed to you, and you will find no refuge besides Him if you do not do so.
Then, Allah, Glorified be He, gives His Prophet, may Allah bless him and grant him peace, some important instructions: Patiently stay with your companions who sincerely worship their Lord alone and call upon Him morning and evening, seeking His good pleasure. Do not turn your attention away from them to the rich and noble unbelievers, thereby seeking their company; and do not obey those whose hearts We have made heedless of Our remembrance, who follow their whims and whose deeds are marked by heedlessness and are doomed to utter loss.
Next, Allah instructs His Prophet, may Allah bless him and grant him peace, to openly proclaim the truth: Say to the heedless, ‘What I have brought you is the truth from your Lord. let him who wills, believe in it, and let him who wills, reject it.’ We have prepared for the unbelievers a terribly fierce fire whose walls will surround them from all sides; and if they beg for water to quench their intense thirst, they will be given extremely hot black, stinking water which will scald their faces. What a horrible drink, and what a terrible resting place!