(7) You shall not swear falsely by the name of the LORD your God; for the LORD will not clear one who swears falsely by His name.
Questions to Ponder:
When is it appropriate to use God's name?
Does it matter if the reason is true or false?
Why are the punishments so extreme for swearing while using God's name?
Is this law written for God's sake or humanity's sake?
(Rashi's Question: How does one define 'in vain'?)
לשוא IN VAIN — for no valid reason, idly. What is a שבועת שוא, an oath taken for no valid reason? If one takes an oath declaring something, the nature of which is evident, to be different from what it is: e. g., swearing about a stone pillar that it is of gold (Shevuot 29a).
לשוא, committing perjury thereby; without doubt this oath will backfire on the one uttering it; כי לא ינקה ה' את אשר ישא את שמו לשוא, for having used His holy name to utterly no purpose. Even if the person swearing such an oath had spoken the truth he will not be free from this sin, how much more so if someone used G’d’s name to swear falsely. It is not compatible with G’d’s honour and dignity that man use His Holy name for his own ends. The only time such an oath is permissible, or in some instances even mandatory, is when it is impossible to arrive at the truth by any other means there being no witnesses to the matter under dispute. As far as swearing a false oath, i.e. perjuring oneself is concerned, the Torah has a separate commandment in Leviticus 19,12 spelling this out. ולא תשבעו בשמי לשקר, “and you must not swear an oath in My name when that oath is a lie.”
What is the difficulty with using God's name when telling the truth?
The entire world trembled when the Holy One, Blessed be He, said at Mount Sinai: “You shall not take the name of the Lord, your God, in vain, for the Lord will not hold guiltless one who takes His name in vain” (Exodus 20:7). And be aware that with regard to all of the other transgressions in the Torah it is stated: “And will…clear the guilty [venakkeh]” (Exodus 34:7); whereas here, with regard to taking a false oath, it is stated: “Will not hold guiltless [lo yenakkeh].” And be aware that with regard to all of the other transgressions in the Torah, punishment is exacted only from the transgressor, whereas here, punishment is exacted from him and from his family, as it is stated: “Do not allow your mouth to bring your flesh into guilt” (Ecclesiastes 5:5).