Must a lawsuit be formally written down before a judge hears it?

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A judge does not hear a lawsuit unless it is formally documented (muharrarah), except concerning a bequest (wasiyyah) or an admission (iqrar). This is because the judge questions the defendant regarding the claim; if the defendant admits it, it becomes binding. A defendant cannot be bound by an unknown claim. This differs from an admission because the right is against the admitter, and thus the right is not extinguished by failing to prove its exact details. A claim regarding an unknown bequest is valid because a bequest of an unknown item or share is valid; therefore, one can only claim it as it was established (i.e., unknown). Similarly, an admission of an unknown item is valid, so it is valid for the opposing party to claim that the defendant admitted to an unknown amount.