דברים, פרק ה׳, פסוק י״א

The instruction regarding the use of God's name carries immense weight, marking a severe and unforgivable act. The prohibition goes far beyond malicious deceit or perjury; it encompasses any casual or unnecessary use of the divine name, echoing the principles established during the initial giving of the Ten Commandments [העמק דבר]. The warning strictly forbids swearing by God's name, making it clear that God will not forgive or exempt the sinner from punishment [ביאור שטיינזלץ].

The command repeats the concept of vanity to convey two distinct ideas. The primary approach among commentators is that the initial warning forbids swearing for no reason at all, while the subsequent warning specifically addresses a false oath. The underlying logic here is preventative. If a person makes a habit of using God's name casually, even when speaking the truth, this routine will eventually lead him to swear falsely. Once that line is crossed, the sinner will not be cleared of guilt. Furthermore, using God's name for absolutely no purpose is inherently a statement disconnected from truth [ברכת אשר על התורה].

Desecrating God's name is considered a far graver sin than many others, and it offers no path to atonement [ביאור שטיינזלץ]. The profound severity of this act is reflected in a linguistic connection drawn by commentators, where the concept of vanity is linked to the underworld, teaching that one who swears falsely is destined to descend into the abyss [שפתי כהן].

The placement of this command immediately before the obligation to keep the Sabbath is deeply intentional. Both commandments share the core theme of desecration. Just as taking a false oath is defined as a desecration of God's name, working on the Sabbath is an act of desecrating its holiness. Placing them side by side highlights the strict duty to protect both of these sacred values from violation [קיצור בעל הטורים].