يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَكُونُوا كَالَّذِينَ كَفَرُوا وَقَالُوا لِإِخْوَانِهِمْ إِذَا ضَرَبُوا فِي الْأَرْضِ أَوْ كَانُوا غُزًّى لَّوْ كَانُوا عِندَنَا مَا مَاتُوا وَمَا قُتِلُوا لِيَجْعَلَ اللَّهُ ذَٰلِكَ حَسْرَةً فِي قُلُوبِهِمْ ۗ وَاللَّهُ يُحْيِي وَيُمِيتُ ۗ وَاللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ (156)
(3:156) Believers, do not behave like those who disbelieved and say to their brothers (who meet some mishap) in the course of their journey for fighting: 'Had they remained with us, they would not have died nor been slain.' Allah makes such thoughts the cause of deep regrets in their hearts. *113 For in truth it is Allah alone who grants life and deals death. Allah sees all that you do.
*113). Such ideas had no solid ground. God's decree regarding the time of one's death cannot be deferred. Those who lack faith in God and think that everything is dependent on their own scheming and effort rather than on the overpowering Will of God become victims of perpetual remorse, since they never cease to reflect how a slightly different circumstance or slightly altered strategy could have led to an altogether different and wholesome result.