Halakhah su Levitico 19:12

That He prohibited us from desecrating [God's] name. And that is the opposite of the sanctification of [God's] name, the explanation of which preceded in the ninth of the Positive Commandments. And that is His, may He be blessed, saying, "And you shall not desecrate My holy name" (Leviticus 22:32). And this sin is divided into three parts - two that are general (for all) and one which is specific. Indeed the first of the general ones is anyone who it was demanded of him that he transgress one of the commandments at the time of a religious persecution (shemad) - and the persecutor had in mind to make him sin - whether one of the light commandment or [one] of the weighty commandments; or one who it was demanded of him that he transgress with regards to idolatry, sexual immorality or murder, even if it was not at the time of a religious persecution. Behold [such a one] is obligated to release himself and be killed, and not to transgress - as we explained in the ninth of the Positive Commandments. But if he transgressed and was not killed, he has already desecrated [God's] name and violated this negative commandment. And if the transgressor was in a public place - meaning [in front of] ten Israelites - he has already desecrated [God's] name in public. And he has violated the negative commandment of, "And you shall not desecrate My holy name," and his sin is very great. However he is not lashed, as he was under duress. For a court may only administer the punishment of lashes or a death penalty when volitional - willingly, with witnesses and a warning. And the language of the [Sifra] (Sifra, Kedoshim, Section 4:5) about the one who gives of his offspring to Molekh - "And I will set My face against that man" (Leviticus 20:3): They said, "'That [man],' and not one under duress, and not one inadvertent and not one mistaken." Behold it has already been made clear to you that one who worships an idol under duress is not liable for excision nor - all the more so - a death penalty of the court. But he has transgressed [the prohibition of] desecration of [God's] name. And the second part that is also general is when a man does a sin for which he has no desire and no benefit, but rather intends [to show] rebellion or the removal of the yoke of the kingdom of Heaven with his action. Behold this one also desecrates [God's name] and is lashed. And hence He said, "[You shall not swear falsely by My name,] and desecrate the name of your God" (Leviticus 19:12). For this one intends to anger [God] with this matter, and he has no physical benefit with it. And the specific part is when a man known for his virtue and goodness does a certain action that appears like a transgression in the eyes of the masses; such that it is not appropriate for someone esteemed to do this type of action, even though the action is permissible. And that is their saying (Yoma 86a), "What are the circumstances of the desecration of [God’s]name? [Rav said,] 'For example, [someone like] me, if I take meat from a butcher and do not give him money immediately.' [...] Rabbi Yochanan said, 'For example, [someone like] me, if I would walk four cubits without Torah and without tefillin.'" And this command was already repeated, when He said, "and do not desecrate the name of the Lord." And the regulations of this commandment have already been explained in Pesachim, in Sukkah and in Yoma. (See Parashat Emor; Mishneh Torah, Foundations of the Torah.)

To not swear about the denial of money: To not swear about the disavowal, as it stated (Leviticus 19:11), "and you shall not lie" - meaning to say that if a man denied a deposit, he transgressed, "you shall not disavow"; and if he swore about the denial afterwards, he transgressed, "and you shall not lie." As so has the understanding of this verse come to us, that it is to warn about one who swears about the denial of money. And [it is] like it appears in Sifra, Kedoshim, Section 2:3, "'And you shall not lie' - what do we learn to say? Since it is stated (Leviticus 5:22), 'and he swears falsely,' we have learned the punishment. From where is the warning? [Hence,] we learn to say, 'and you shall not lie.'" And it is elucidated in Tractate Shevuot 49b that anyone who swears an oath about the denial of money, transgresses two negative commandments - on account of "And you shall not swear in My name falsely" (Leviticus 19:12), and on account of "and you shall not lie towards your compatriot."

To not swear falsely: To not swear falsely, as it is stated (Leviticus 19:12), "And you shall not swear in My name falsely." And they, may their memory be blessed, explained (Shevout 21a) that this verse warns about an oath of speech. And an oath of speech is what is stated in the Torah (Leviticus 5:4), "Or a soul that swears to express with the lips to do bad or to do good." And it is divided into four parts - two of the future and two of the past, such as swearing on something that was done or not done, and on something that in the future he will do or will not do. And an oath of speech is only practiced with things that it is possible for a person to do, whether in the past or in the future. How is of the past? "I ate," or "I did not eat"; and so [too,] "I threw," or "I did not throw a stone into the sea." And how is of the future? "I will eat," or "I will not eat"; or "I will throw," or "I will not throw." But with things that have a prevention from the Torah, an oath of speech is not practiced. As an oath only rests upon an optional matter - that if he wants, he does it and if he wants, he does not do it - as it is stated, "to do bad or to do good." But with any matter of a commandment, there is an obligation upon him to do it. Therefore an oath of speech does not rest upon him, whether in the past or in the future - in the case that he swears to perform a commandment, and he did not perform it; and so [too,] if he swears that he performed a commandment, and he did not perform it. As [just] like a liability [for punishment for a false oath] does not rest upon the matter of a commandment in the future, so too does it not rest upon it in the past. And so is the matter elucidated in its place in Shevuot 27a.