Allah says;
أولم ينظروا في ملكوت السماوات واﻻرض وما خلق الله من شيء وأن عسى أن يكون قد اقترب أجلهم
Do they not look in the dominion of the heavens and the earth and all things that Allah has created; and that it may be that the end of their lives is near.
Allah asks, those who denied faith, did they not contemplate about Our Ayat in the kingdom of the heavens and earth and what was created in them! Do they not contemplate about all this and learn lessons from it, so that they are certain that He Who has all this, has no equal or rival All this was made by He Who Alone deserves the worship and sincere religion, so that they might have faith in Him and believe in His Messenger, all the while turning to Allah's obedience, rejecting any rivals to Him, and rejecting idols. They should be warned that their lives may have reached their end, and they, thus, face their demise while disbelievers, ending up in Allah's torment and severe punishment.
Allah said,
فبٲي حديث بعده يومنون
In what message after this will they then believe!
Allah says, what more warnings, and discouragements should compel them to believe, if the warnings and threats that Muhammad brought them from Allah in His Book do not compel them to do so