A.T. Robertson Commentary John 8:47

"He that is of God heareth the words of God: for this cause ye hear [them] not, because ye are not of God." — John 8:47 (ASV)

He that is of God (ο ων εκ του θεου). See this use of εκ in 3:31f. "Their not listening proved that they were not of God" (Dods). They were of the earth and the devil, not of God.