Augustine of Hippo — as excerpted in the Catena Aurea on John 8:44-47

“(xi. de Civ. Dei, c. xiv) Or when our Lord says, The truth is not in him, He intends it as an index: as if we had asked Him, how it appeared that the devil stood not in the truth; and He said, Because the truth is not in him. For it would be in him, if he stood in it.”