As Allah the Exalted says, “Or do you possess a clear authority? Then bring your book, if you are truthful” (37:156–157). He also says, “They are nothing but names you and your fathers have invented; Allah has sent down no authority for them” (53:23). And He says, “Have We sent down to them an authority that speaks about the partners they ascribe?” (30:35).

The reason is that a proof empowers its bearer over his opponent: whoever holds the proof enjoys authority and ascendancy over his adversary (1), even if he is unable to overcome him with physical force.

This is one of the ways by which Allah supports (2) His messengers and the believers in this world, as He, the Exalted, says: “Indeed, We will assuredly aid Our messengers and those who believe, in the life of this world and on the Day when the witnesses will stand forth” (40:51).

Since martial contests were legislated to enable the believer to learn combat, become accustomed to it, and train for it, it is clear that the combatant may sometimes aim merely to repel the enemy when he himself is being pursued and the enemy is the pursuer; at other times he may intend to seize the initiative and overcome the enemy from the outset when he is the pursuer and the enemy the one pursued; and he may at times intend both objectives together. Thus there are three situations in which the believer is commanded to wage jihad.

Defensive jihad is harder than offensive jihad, for it resembles the case of warding off an assailant; for this reason the one who is wronged is permitted to defend himself.