﴿ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَكُونُوا۟ كَٱلَّذِينَ كَفَرُوا۟ وَقَالُوا۟ لِإِخْوَٰنِهِمْ إِذَا ضَرَبُوا۟ فِى ٱلْأَرْضِ أَوْ كَانُوا۟ غُزًّۭى لَّوْ كَانُوا۟ عِندَنَا مَا مَاتُوا۟ وَمَا قُتِلُوا۟ لِيَجْعَلَ ٱللَّهُ ذَٰلِكَ حَسْرَةًۭ فِى قُلُوبِهِمْ ۗ وَٱللَّهُ يُحْىِۦ وَيُمِيتُ ۗ وَٱللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌۭ ﴾

“O you who have attained to faith! Be not like those who are bent on denying the truth and say of their brethren [who die] after having set out on a journey to faraway places or gone forth to war, "Had they but remained with us, they would not have died," or, "they would not have been slain" - for God will cause such thoughts to become a source of bitter regret in their hearts, since it is God who grants life and deals death. And God sees all that you do.”

Then Allah said to the Companions of Muhammad: (O ye who believe!) in Muhammad and the Qur'an. (Be not) in war (as those who disbelieved) in secret, i.e. 'Abdullah Ibn Ubayy and his followers who returned to Medina (and said of their brethren) the hypocrites (who went abroad in the land) who journeyed with the Companions of Muhammad (or were fighting in the field) or went with their Prophet in a fighting expedition: (If they had been (here) with us) in Medina (they would not have died) on their journey (or been killed) during the fighting expedition; (that Allah may make it) make that doubt (anguish) grief (in their hearts. Allah giveth life) on the journey (and causeth death) settlement; (and Allah is Seer of what ye do) of what you say.