Jihad

O you who believe! Take your precautions, and either go forth (on an expedition) in parties, or go forth all together.

There is certainly among you he who would linger behind (from fighting in Allâh's Cause). If a misfortune befalls you, he says, "Indeed Allâh has favoured me in that I was not present among them."

But if a bounty (victory and booty) comes to you from Allâh, he would surely say - as if there had never been ties of affection between you and him - "Oh! I wish I had been with them; then I would have achieved a great success ( a good share of booty)."
Let those (believers) who sell the life of this world for the Hereafter fight in the Cause of Allâh, and whoso fights in the Cause of Allâh, and is killed or gets victory, We shall bestow on him a great reward.

An-Nisa 71-74