Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths:
God condemned not only perjury but lightness in swearing itself, which diminishes reverence for His name. The Jews imagined guilt lay only in false oaths, but Christ reproves this gross error: they thought they might abuse God's name freely so long as they did not swear falsely. When a man employs God's name and then cheats his neighbor, he injures God as well as man.
AI summary
Perjury is impiety toward God and injustice toward man combined; it renders a man obnoxious to divine wrath. The ancients understood this so well they turned their swearing formulas into curses upon themselves, wishing God's judgment if they lied. This shows how deeply nations have always felt that God must curse the false swearer, if He be God.
AI summary
Commenting on Matthew 5:33-37
The Jews concerned themselves only with the truth of an oath, not its vanity. They swore by creatures, thinking this binding them to nothing, since God's name was not invoked. They thought vows to the Lord alone obliged them, and oaths by others did not. This narrow reading left them free to swear endlessly without conscience.
AI summary