Overall meaning :
Allah Almighty opens this noble surah with one of the disconnected letters of the Arabic alphabet, namely qaaf. A brief discussion of these disconnected letters is to be found at the beginning of Surat Al-Baqarah.
I swear by the Glorious Qur’an containing exalted and sublime meanings [that you, Muhammad, are a true messenger and that the Day of Resurrection and Recompense is true]. The Quraysh unbelievers deem it strange that a human messenger from among themselves has come to them to warn them of Allah’s punishment, and so they say, ‘It is indeed a wondrous thing that a human messenger has come to us! What! After we have become dust, shall we indeed be brought back to life again?! Such a return to life is utterly impossible!’
We know very well what the earth consumes of their bodies after their death, and with Us is a well-preserved Record in which everything is recorded. Indeed, they deny the Qur’an after it has come to them, and so they are now in a state of utter confusion!