يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَكُونُوا۟ كَٱلَّذِينَ كَفَرُوا۟ وَقَالُوا۟ لِإِخْوَٰنِهِمْ إِذَا ضَرَبُوا۟ فِى ٱلْأَرْضِ أَوْ كَانُوا۟ غُزًّى لَّوْ كَانُوا۟ عِندَنَا مَا مَاتُوا۟ وَمَا قُتِلُوا۟ لِيَجْعَلَ ٱللَّهُ ذَٰلِكَ حَسْرَةً فِى قُلُوبِهِمْ ۗ وَٱللَّهُ يُحْىِۦ وَيُمِيتُ ۗ وَٱللَّهُ بِمَا تَعْمَلُونَ بَصِيرٌ
Commentary:
The expression, when they travel in the land, means, when they travel in the land in the cause of God. This meaning is supported by the context.
The idea contained in the words, so that Allah may make it a cause of regret in their hearts, is that when Muslims refused to act upon the advice of disbelievers not to fight, and instead, came forth in large numbers to fight in the way of God, the disbelievers were naturally grieved at their failure to win them over to their way of thinking.
The interpretation of the clause, and Allah gives life and causes death, would vary according to the different meanings of the words موت (death) and حیاة (life) occurring in it. If the death referred to in the verse is taken in the sense of destruction, the clause would mean that with the death of a few Muslims, Islam would not go to ruin. God has decreed to vouchsafe victory to Muslims and the death in fighting of a number of the victorious army cannot possibly result in their destruction. If, however, death is here taken to mean "disgrace", then the clause would mean that God’s votaries and true servants never meet with disgrace because all honour is in His hands and He gives it to whomsoever He pleases. Truly speaking, he who fights and lays down his life in the cause of truth can in no sense be regarded as dead, because such a one gives his life for the sake of Him Who is the controller of all life and death. Such a person can never die; for though physically he may die, spiritually he lives forever. In this connection, see also 2:155.
When they travel in the land in the cause of God.
The object of disbelievers was to frighten the Muslims in order to make them keep away from fighting, but the Muslims, far from being discouraged by such warnings, became all the more firm in their resolve to fight the disbelievers. This filled the disbelievers with regret for having made the effort which produced a result opposite to that which they had desired.