How should Zakat funds allocated to a fighter (Ghāzī) be distributed, and what happens if he does not engage in the intended expedition?

Primary text

If it is established that the recipient intends to fight, his claim is accepted because verifying his inner intention (niyyah) through evidence is impossible. He is given sufficient amount for his sustenance, purchase of arms, a horse if he is a cavalryman, his baggage, armor, clothing, and all other necessities for his expedition, even if the amount is large. This payment is conditional (daf'un murā'ā). If he does not fight, he must return what he received because it was given based on that specific purpose. If he fights and returns, he possesses what he received, as sufficiency was provided to him, and any personal restriction he imposed upon himself is irrelevant. If he sets out but returns from the path, or fails to complete the expedition for which the funds were given, he must return any excess remaining, as the purpose for which he received it was not fully realized.