Say:"The appointment to you is for a Day, which you cannot for an hour move back nor forward."meaning, `you have an appointed time which is fixed and cannot be changed or altered. When it comes, you will not be able to put it back or bring it forward,' as Allah says:إِنَّ أَجَلَ اللَّهِ إِذَا جَأءَ لَا يُوَخَّرُVerily, the term of Allah when it comes, cannot be delayed. (71:4)وَمَا نُوَخِّرُهُ إِلاَّ لاًّجَلٍ مَّعْدُودٍيَوْمَ يَأْتِ لَا تَكَلَّمُ نَفْسٌ إِلاَّ بِإِذْنِهِ فَمِنْهُمْ شَقِىٌّ وَسَعِيدٌAnd We delay it only for a term (already) fixed. On the Day when it comes, no person shall speak except by His leave. Some among them will be wretched and (others) blessed. (11:104-105)