Bede : And when David had no sword in his hand, etc. When he had no one and the Lord of his word's minister, through whom he might shatter the pride of the devil by teaching, except whom he himself had first snatched victoriously from the devil; for all are by nature children of wrath, all conceived in iniquities, and in sins are generated by the mother (Ephesians V; Psalm L); he came unexpectedly, and the adversary long strong, as a stronger surpassing him, took away all his weapons, in which he trusted, so that through those whom the enemy previously as his weapons used to kill the souls of the wretched, through them afterward the Savior, transformed into weapons of righteousness, may cut off the head of iniquity from its body, that is, compel those converted to faith to anathematize Satan, and renounce all his works and pomps. And rightly is it recounted that David first took the sword with which he slew the Philistine by his hand, and drew it out of its sheath; because every great and strenuous one of the devil's empire, whom the Lord first receiving by his visitation of piety, draws out from the obscure hiding places of errors into the light of liberating grace; and so through him also allows others to be similarly corrected and reproved. But we too, when disputing against the madness of heretics, we convict them as fabricators of lies and cultivators of perverse doctrines, either by the arguments or by the testimonies of Scripture which they themselves had proposed to bring us back; indeed, with the giant's own sword we strike down his insolence. — Commentary on Samuel