Not holding back

O believers, do not be like those who disbelieve and say about their brothers who travel or go to battle, ‘If they had stayed with us, they would not have died or been killed.’ Allah makes such thoughts a source of regret in their hearts. It is Allah who gives life and causes death.

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.

3:168Those who, while they sat at home, said of their brethren (who were fighting for the cause of Allah): If they had been guided by us they would not have been slain. Say (unto them, O Muhammad): Then avert death from yourselves if ye are truthful.

4:72Lo! among you there is he who loitereth; and if disaster overtook you, he would say: Allah hath been gracious unto me since I was not present with them.