Who is obligated to participate in a general military levy (Nafir)?

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The general military levy (Nafir) encompasses all able-bodied individuals, regardless of whether they are wealthy (mukthir) or poor (muqill), when the enemy approaches their territory. No one is permitted to stay behind except those whose presence is necessary to guard the homeland, family, and wealth, those specifically exempted by the commander, or those physically incapable of participating or fighting. This is mandated by Quran 9:41 ('March forth, light and heavy') and the Prophet’s command, 'When you are summoned to march, then march.' Furthermore, God condemned those who sought to return to their homes during the Battle of the Trench, indicating the obligation when the enemy arrives, making Jihad an individual obligation upon all who are capable.