What is the validity of granting authorization (ijazah) by individuals lacking full legal capacity?

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Authorization (ijazah) is only valid when issued by someone capable of disposition. Authorization issued by a minor (sabi), an insane person (majnun), or someone restricted due to foolishness (mahjur 'alayhi li-sufh) is invalid. This is because authorization constitutes a gratuitous transfer of wealth (tabarru' bi-l-mal), which is invalid for these individuals, similar to a gift (hibah). Regarding an individual restricted due to bankruptcy (mahjur 'alayhi li-filas), the validity of authorization depends on its legal nature: if it is considered a gift, it is invalid; if it is considered a ratification (tanfidh), it is valid.