Yerushalmi Shevuot 3:9 ירושלמי שבועות ג׳:ט׳

MISHNAH: “An oath that I shall eat this loaf; an oath that I shall not eat it.” The first one is a blurted oath, the second a vain oath¹³³Since by the first oath he became obligated to eat the loaf by biblical rules, the second oath has a similar status as an oath to violate a biblical commandment.. If he ate it he violated a vain oath, if he did not eat it he violated a blurted oath.

HALAKHAH: “A blurted oath,” etc. ¹⁵¹There is a parallel in Nedarim3:2, Notes 74–78, which is not an exact copy. While repeated vows are separate obligations, of repeated identical oaths only the first is valid; the others are vain oaths. There is no notion of a vain vow.“ ‘An oath that I shall not eat this loaf, an oath that I shall not eat it’, he is liable only once”¹⁰⁰He made three oaths but the second and third are void since they forbid what already is forbidden.. Something which would be forbidden for vows and is permitted for oaths¹⁵²It is not really permitted for oaths since the second oath is vain, but the second never has the status of a valid oath.. Not on this was it said but on the following: “Whether matters of himself⁷¹All the rules of liability for a variable value sacrifice spelled out in the preceding Mishnaiot are valid for all kinds of oaths irrespective of their content or meaning., or matters of others,” as Rebbi Abba said in the name of Samuel: ‘An oath that X gave a mina to Y.’ If it turns out that he had not given, since it is not in his hand for the future it is not in his hand for the past⁷⁵He never could swear that X will give Y since it is not in his power to force X to give. This is all about liability for a variable sacrifice, not monetary liabilities. Since witnesses do not swear, this is not a case of perjury.. It was found stated on both cases: This is more stringent for the past than for the future: If he says “I shall not eat, I shall not eat,” he is liable only once. “I did not eat, I did not eat,” he is liable for each single time¹⁵³In the first case, the first oath creates a prohibition; no oath can be made concerning an existing prohibition. In the second case, a false statement is reinforced by an oath; there is no upper limit on the number of lying oaths a person might make..

“An oath that I shall eat this loaf; an oath that I shall not eat it.” The first one is a blurted oath, the second a vain oath¹³³Since by the first oath he became obligated to eat the loaf by biblical rules, the second oath has a similar status as an oath to violate a biblical commandment.. How does one deal with him? One tells him to eat; it is better to break a vain oath than a blurted one¹⁵⁴The reading of Rosh (#24) is: It is better to break a vain oath than blurted and vain ones. The two oaths have completely different status: Since the second one is vain at the moment it is made, the making of the vow is sinful and its maker is liable to be flogged. The only active oath is the first and this one has to be kept..

“An oath that I shall not eat this loaf; an oath that I shall eat it.” The first one is a blurted oath, the second a vain oath. How does one deal with him? One tells him not to eat; it is better to break a vain oath than to break a vain and a blurted one.

“An oath that I shall eat this loaf today; an oath that I shall not eat it today.” Then he ate it. Rebbi Joḥanan said, he kept the first oath and invalidated the second¹⁵⁵For R. Joḥanan, the valid first oath prohibits the making of the second which automatically becomes a vain oath subject to the statutory punishment for vain oaths but irrelevant as oath. R. Simeon ben Laqish notes that the first oath contains a promise, not a prohibition. Therefore, there is no rule which prohibits making the second oath. Making the second oath is sinful because it invalidates the first but from the point of view of the law of oaths it is possible. Since he becomes liable for punishment for breaking the first oath, the second is active and should be kept. By eating the loaf, the person commits a second sin.
The Babli, 28b, has a completely different taking on this problem and refers it to the problem whether a criminal warning is possible if it is not clear that a criminal act was intended (Note 104).. Rebbi Simeon ben Laqish said, he invalidated the first one and did not keep the second.

“An oath that I shall not eat this loaf today; an oath that I shall eat it today.” Then he ate it. Rebbi Joḥanan said, he invalidated the first oath and kept the second¹⁵⁶Swearing the second oath was a criminal act. Since the second is not a prohibition, it can be fulfilled.. Rebbi Simeon ben Laqish said, he invalidated the first one. One tells him to keep the second with another loaf¹⁵⁷Since he said אֹכְלֶנָּה “I shall eat it” and not אֹכַל כִּכָּר זוֹ “I shall eat this loaf” it is better to interpret it as not referring to the same loaf as does the first oath. Then while nothing can be done to mitigate the sin of breaking the first oath, the second oath can be changed from a vain oath to a new, valid oath referring to something different, not connected with the first..

“An oath that I shall eat this loaf today; an oath that I shall eat it today.” Then he ate it. Rebbi Joḥanan said, he kept both of them. Rebbi Simeon ben Laqish said, he kept the first one and one tells him to keep the second with another loaf¹⁵⁸This is a situation similar to the preceding one. For R. Joḥanan, the second oath is vain, subject to punishment as such, but kept by keeping the first. For R. Simeon ben Laqish the second oath is not vain if it is interpreted as referring to another loaf; both oaths can be kept without sin..

“An oath that I shall not eat this loaf today; an oath that I shall not eat it today.” Then he ate it. In Rebbi Joḥanan’s opinion he is twice liable¹⁵⁹Once for breaking the oath, and once for uttering a vain oath.. Is he only once liable in Rebbi Simeon ben Laqish’s opinion¹⁶⁰By referring the second oath to an indefinite other loaf.? Even Rebbi Simeon ben Laqish agrees that he only emphasizes the prohibitions¹⁶¹In this case, R. Simeon ben Laqish might agree that the repetition indicates reinforcement and that any reasonable interpretation must refer both oaths to the same loaf, agreeing in this case with R. Joḥanan..