The one who has the responsibility to dispose the affairs of the creation in accordance to His knowledge, perfect power and all-encompassing wisdom. The one who looks after His friends and makes the good easy for them, preserves them from evil and suffices for them in all of their affairs. Therefore the one who takes Him as one to be relied upon, He suffices him.
“Allah is the Friend of those who believe, He guides them from the darknesses into the light.”
[al-Baqarah (2): 257]
“Such is Allah your Lord! None has the right to be worshipped but He, the Creator of all things. So worship Him Alone, and He is the Wakil over everything.”
[al-An'am (6): 102]
“And put your trust in Allah, for Allah is sufficient as Wakil.”
[al-Ahzab (33): 3]
From “Explanation to the Beautiful and Perfect Names of Allah” — Shaykh as-Sa’di (d.1376H)