Gregory the Great — as excerpted in the Catena Aurea on John 8:31-36

“(iv. Mor. c. 42. in Nov. Ex. 21) Because whoever yields to wrong desires, puts his hitherto free soul under the yoke of the evil one, and takes him for his master. But we oppose this master, when we straggle against the wickedness which has laid hold upon us, when we strongly resist habit, when we pierce sin with repentance, and wash away the spots of filth with tears.”