Quran 3, Ali 'Imran (House of Imran) ⓘ

3:156O ye who believe! Be not as those who disbelieved and said of their brethren who went abroad in the land or were fighting in the field: If they had been (here) with us they would not have died or been killed: that Allah may make it anguish in their hearts. Allah giveth life and causeth death; and Allah is Seer of what ye do.

يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَكُونُوا كَالَّذِينَ كَفَرُوا وَقَالُوا لِإِخْوَانِهِمْ إِذَا ضَرَبُوا فِي الْأَرْضِ أَوْ كَانُوا غُزًّى لَوْ كَانُوا عِنْدَنَا مَا مَاتُوا وَمَا قُتِلُوا لِيَجْعَلَ اللَّهُ ذَلِكَ حَسْرَةً فِي قُلُوبِهِمْ وَاللَّهُ يُحْيِي وَيُمِيتُ وَاللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ