Athanasius of Alexandria, on Ps 13:1

“Unto the end, a psalm for David. The fool hath said in his heart: There is no God, They are corrupt, and are become abominable in their ways: there is none that doth good, no not one.”

“This statement [about fools] is directly followed by one pointing out that their actions correspond with their thoughts: "They are corrupt, and their behavior is evil." The unrighteous person corrupts his body in every possible way: stealing, committing adultery, cursing, getting drunk, and doing similar things.… Count on it: those who are fools in their thoughts will do wicked deeds. As the Lord said [to the Pharisees], "How can you speak good things when you are evil?" And they truly were evil, because their thoughts were wicked.”

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