O believers! Do not be like the unbelievers who speak of those brethren of theirs who die during their travels on the earth or while engaged in fighting: “Had they but stayed with us they would not have died or been killed.” Allah makes such thinking a cause of regret and anguish in their hearts. It is Allah who gives life and death. Allah is observant of all your actions.
Meaning:-
Brethren: fellow members, brothers.
Anguish: suffering, or pain.