Ambrose of Milan, on Rom 3:4

“But God is true; and every man a liar, as it is written, That thou mayest be justified in thy words, and mayest overcome when thou art judged.”

“Does God lie? Truly He lies not, because it is impossible for God to lie. And further, does this impossibility arise from infirmity? No, truly, for how can He be Almighty if He cannot do all things? What then is impossible to Him? Not that which is difficult to His Power, but what is contrary to His Nature. It is impossible, it is said, for Him to lie. This impossibility comes not of infirmity, but of Power and Majesty, for truth admits not of falsehood, nor God's Power of the weakness of error. Wherefore let God be true and every man a liar.”

Imported from an open dataset — not yet checked against the printed edition.