8. Al-Muhaymin (المهيمن) ― the Guardian ― means with regard to Allah (Great and Glorious), the one who tends His creatures with regard to their actions, their sustenance, and the time of their death. He tends to them by His cognizance, His possession, and His protection. Everyone who has complete command of a situation, who takes possession of it and protects it, will be its ‘guardian’. Taking command comes down to knowledge, possession to the perfection of power, and protection to action. The one who unites these meanings is named guardian. But only Allah (Great and Glorious) joins them absolutely and perfectly, so it was said: it is one of the names of Allah the Most High recorded in ancient writings.
Every servant who watches over his heart until he supervises its depths and its secrets, and also takes possession of reforming his inner states and attributes, and undertakes to protect it continuously according to the requirements of his reform, will then be ‘guardian’ in relation to his heart.
― Imam al Ghazali’s (rahmatullah ‘aleyh) 99 Beautiful Names of Allah