That the tares are first separated, signifies that by tribulation the wicked shall be separated from the righteous; and this is understood to be performed by good Angels, because the good can discharge duties of punishment with a good spirit, as a judge, or as the Law, but the wicked cannot fulfil offices of mercy.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Quaest. Ev., i, 10