Saint Hilary worked tirelessly to defend the faith from wrong-thinking Christians, typically called heretics. What follows is Hilary's teaching on God the Father.
It is the Father from whom everything that exists has been formed. He is in Christ and through Christ the source of all things. Moreover, His being is in Himself and He does not derive what He is from anywhere else, but possesses what He is from Himself and in Himself. He is infinite because He Himself is not in anything and all things are within Him; He is always outside of space because He is not restricted; He is always before time because time comes from Him.... But, God is also present everywhere and is present in His entirety wherever He is. Thus, He transcends the realm of understanding, outside of whom nothing exists and of whom eternal being is always characteristic. This is the true nature of the mystery of God; this is the name of the impenetrable nature in the Father.
(On the Trinity, Bk. 2, Ch.6; ML 10, 54; FC XXV, 39-40)
The Liturgical prayer for Saint Hilary may be prayed here.