Imam al-Sadiq (as) said: “No creature can comprehend anything except through God. And the knowledge of God cannot be achieved except through God. God is empty of His creation and His creation is empty of Him.” (Al-Tawhid)

Al-Mizan says: According to this narration, God is known to any creature that has any share of knowledge of anything. This knowledge is not a sort of contemplative knowledge that one acquires through instruments, indications and data. 

But how is it that God is known to every knower (of anything)? No created being can be found in any mode of existence unless it is supported by God and the being relies on Him. Without the Cause, the effect would vanish. Now, the knower is also created, which means that it depends on God in all its aspects including its knowledge, because the entire existence of the knower is supported by God. Both the knower and what is known relies on God in order to be a knower and known. On the side of the known, God is what is known before anything else. If anything else is known, it is subsequent to knowing God. On the side of the knower, God knows before anything else. If anything else is to know, it is subsequent to God knowing. This is what can be deduced after contemplating on the above tradition and the verse: they do not comprehend anything of His knowledge except what He wills (2:255).

It is now clear that God is ever known to all knowers, because any knowledge about anything can be realized only by knowing Him first and this is a necessary condition to be a knower of anything.

Reference: Al-Mizan English Volume 16, pp. 117-119, first edition, Tawheed Institute Australia Ltd., 2018