How is the taking of possession of a pledge handled if the pledgor is mute (*kharis*)?

Primary text

If the pledgor is mute, but possesses comprehensible writing or established signs/gestures, his status is equivalent to that of a speaking person. If he gives permission to take possession, it is valid; otherwise, it is not. If his sign or writing is not understood, taking possession is not valid. If any of these individuals (who are incapacitated) had previously given permission, that permission is voided by the subsequent condition that afflicted them, meaning possession is not permitted.