The Blindness of Ibn Umm-Maktum

Ibn Umm-maktum was put in charge of Medina at least a dozen times why because he was a sensible man. His blindness did not come into the way of him being basically in effect the temporary mayor of Medina right? He would send delegations out to find out is anybody spying on us and it is said that Ibn Asak mentions that some Bedouins mentioned that they saw two men spying on the camp  these are Thal-Hans they've been zayed.