Shevuos, Chapter 4, Mishnah 13. This mishnah discusses the various expressions that are valid to be considered an oath of testimony, and the names and appellations of Hashem with which one may impose such an oath.
The expressions that create liability for an oath of testimony:
"Mashbia ani aleichem" - "I impose an oath upon you."
"Metzaveh ani aleichem" - "I command you."
"Oser ani aleichem" - "I forbid you," a term of prohibition.
With any one of these expressions the witnesses are liable. The Gemara clarifies that at least with the latter two expressions - "Metzaveh ani aleichem" and "Oser ani aleichem" - he must add the words "bishvuah," "with an oath," since these statements contain no mention of an oath at all: "metzaveh" is nothing more than a term of command, and "oser" is nothing more than the imposition of a prohibition. For this reason the addition of "bishvuah" is required.
What is meant by this addition of "bishvuah"?
The view of Rashi: that the one imposing the oath actually uses one of the Names of Hashem, and that is what is called an oath.
The view of those who disagree: it is enough to say the word "bishvuah" itself, and that is the intent of the mishnah.
By contrast, one who says "bashamayim uva'aretz" - "by heaven and by earth" - is exempt. This is not one of the Names of Hashem, nor do his words contain any mention of an oath, and therefore it is not sufficient.
The Names and appellations that create liability for an oath of testimony:
The Name written with alef and dalet.
The Name written with shin, dalet and yud.
The Name written with tzadi, beis, alef, vav and tav.
All the appellations of Hashem - that He is merciful and gracious, that He is slow to anger, that He is abounding in kindness. These expressions of the attributes of Hashem, as it were, are considered appellations of His Name.
With any one of these Names and appellations, the one imposing the oath creates liability for an oath of testimony.
The status of the appellations in other areas of law:
Now that we have clarified the law of the appellations, we must examine how they apply in other halachos in which the Name of Hashem is mentioned. One of the most severe prohibitions in the Torah is cursing Hashem. One who curses Hashem using one of these appellations is liable; these are the words of Rabbi Meir, and this is a transgression whose penalty is death. The Sages exempt him and say that he is not put to death; nevertheless, even though he is not included in the death penalty, he still transgresses the negative commandment of "lo sekallel" - "you shall not curse." But all of this applies only to cursing Hashem, whereas regarding an oath of testimony the Sages agreed with the opinion of Rabbi Meir, that the appellations are sufficient to create liability, as mentioned above.
"HaMekallel aviv v'imo b'chulan" - one who curses his father or his mother using any one of these substitute names is liable, in the words of Rabbi Meir. Here too Rabbi Meir maintains his position regarding this grave transgression of cursing one's parents, and the Sages exempt him, just as they exempted him in the case of cursing Hashem.
"HaMekallel atzmo v'chavero b'chulan" - one who curses himself or his fellow using any one of the substitute names transgresses a negative commandment. There is no capital transgression here, only a negative commandment, and it is violated even when one uses one of the substitute names of Hashem.
The language of a curse in an oath of testimony:
One who says to the potential witnesses that if they do not come and testify, "Yakecha Hashem" - may Hashem strike you - or who, after hearing the curses written in the Torah, as in the rebuke, said to the witness "v'chen yakecha Elokim" - just as these curses were stated in the rebuke, so may Hashem strike you if you do not come and testify - this is the curse written in the Torah. This is the curse to which the Torah refers in the oath of testimony when it says "v'shama kol alah" - that the witnesses hear the voice of a curse.
And what is the ruling regarding one who speaks in the reverse form: "al yakecha" - may He not strike you - if you testify for me, or "vivarechecha" - and may He bless you - or "v'yeitiv lach" - and may He do good to you - if you testify for me?
Rabbi Meir holds him liable: even for this form of expression he is liable for an oath of testimony, since from an affirmative statement you infer the negative - that if he does not testify, the opposite will befall him.
And the Sages exempt him: we do not hold a person liable for an oath of testimony on the strength of the inference that from an affirmative statement you infer the negative.
In summary: in this Mishnah we learned the expressions that create liability for an oath of testimony - "mashbia", "metzaveh" and "oser" (with the addition of "bishvuah"), the exemption of one who says "bashamayim uva'aretz", the names and substitute names with which the one administering the oath becomes liable, the status of the substitute names in cursing Hashem, in cursing one's father and mother and in cursing oneself and one's fellow, and the forms of the curse - in the dispute between Rabbi Meir and the Sages concerning one who speaks in the language of a blessing.