Athanasius of Alexandria, on Jer 17:10

“I am the Lord who search the heart and prove the reins: who give to every one according to his way, and according to the fruit of his devices.”

“For such things as these serve for exercise and trial, so that, having proved ourselves zealous and chosen servants of Christ, we may be fellow heirs with the saints. For thus Job: "The whole world is a place of trial to people on the earth." Nevertheless, they are proved in this world by afflictions, labors and sorrows, to the end that each one may receive of God such reward as is appropriate for him, as he said by the prophet, "I am the LORD who tries the hearts and searches the reins, to give to everyone according to his ways."”

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