When a person takes an oath that he will not eat anything on that day and he ate less than an olive-sized portion of food, he is not liable. For "eating" does not involve a quantity less than an olive-sized portion. It is as if he partook of less than the minimum measure of a nevelah, a trefe, or the like. 4,:7-8, the prohibition is of Scriptural origin, but the violator is not punished. Accordingly, the Shulchan Aruch (Yoreh De'ah 238:1) rules that it is forbidden for the person who took such an oath to partake of even the slightest quantity of food. If he said: "[I am taking] an oath that I will not eat this substance," and he ate it, he is liable even if the substance concerning which he took the oath is one mustard seed or smaller.
When a person takes an oath that he will not eat on a specific day and drinks, he is liable, because [a prohibition against] eating includes drinking. 22b derives this concept from Deuteronomy 14:23: "And you shall eat before God, your Lord... the tithes of your grain, your wine, and your oil." Implied is that partaking of wine and oil is also eating. Therefore, if he both ate and drank, he is liable only for one set of lashes if he acted willfully or one sin offering if he transgressed inadvertently.
When a person took an oath not to drink on a given day, he is permitted to eat, because [a prohibition against] drinking does not include eating. How much must he drink for him to be liable? It appears to me that he is not liable unless he drinks a revi'it. In contemporary measure, a revi'it is equivalent to 86 cc. according to Shiurei Torah and 150 cc. according to Chazon Ish. as is the case with regard to other prohibitions.
When a person takes an oath that he will not eat on a particular day and partook of many types of food, or he takes an oath that he will not drink on a particular day and partakes of many types of beverages, he is only liable once. Even if he said: "[I am taking] an oath that today I will not eat meat, bread, or beans," and he eats all [these types of food]. He is only liable once. All [of these foods] can be joined together to reach the measure of an olive-sized portion.
🥖 The Olive-Size Rule
An oath not to eat requires a minimum of an olive-size to trigger liability. An oath not to taste has no minimum. Drinking is generally separate from eating — swearing not to eat permits drinking unless the oath explicitly includes both.
When a person takes an oath that he will neither eat nor drink and then eats and drinks, he is liable twice. Although drinking is included in eating, since he specifically said: "And I will not drink," he revealed his intention not to include drinking in eating. Thus it is as if he took an oath on this independently and this independently. Therefore he is liable twice.
Similarly, if a person said: "[I am taking] an oath that I will not eat bread from wheat, bread from barley, or bread from buckwheat," he is liable for each one individually if he partakes of them. He mentioned "bread" three times to make a distinction and cause him to be liable for each one individually.
[The following laws apply when a person's] colleague was persistently imploring him to eat at his [home], telling him: "Come and drink with me, wine, milk, and honey." If he answers: "[I am taking] an oath that I will not drink wine, milk, and honey," he is liable for each one individually if he partakes of them. [To be liable only once,] he should have said: "[I am taking] an oath that I will not drink anything," or "...[that I will not drink] what you said." Since he repeated the phrase, stating each one individually, 3:4)]. he revealed his intention that he obligated himself with an oath for each and every type [of beverage] individually. Therefore [the beverages] are not combined with each other [to reach the minimum measure] of wine and half of a revi'it of milk, he is not liable. and the person is liable only when he eats the minimum measure from each one individually. Since a sin offering is required for each one individually, they are like fat and blood which cannot be combined for [the measure of] an olive-sized portion as explained in Hilchot Ma'achalot Assurot.
[When one says: "I am taking] an oath that I will not eat this loaf," or "...that I will not eat it," once he eats an olive-sized portion of it, he is liable. [If he says:] "[I am taking] an oath that I will not eat it up," he is not liable until he eats the entire loaf. If he says: "[I am taking] an oath that I will not eat this loaf; [I am taking] an oath that I will not eat it up," should he eat it, he is liable only once.
Similarly, if one said: ["I am taking] an oath that I will not eat today," and then took an oath concerning a loaf that he would not eat it up, [even though] he eats the entire [loaf] that day, he is not liable only once. Similar laws apply in all analogous situations. [The rationale is that] an oath does not take effect when another is already in effect. applies only with regard to matters that are dependent upon one's volition, not on those forbidden by the Torah (Chapter 5, Halachah 17). Accordingly, once something is forbidden by an oath, it is no longer a matter dependent on one's volition. Hence, a sh'vuat bitui cannot take effect (Kiryat Sefer). As stated in Chapter 6, Halachah 17, if the person has the first oath nullified, the second oath takes effect. If, however, one took an oath that he would not eat up a loaf and afterwards, took an oath that he would not eat anything or that he would not eat this loaf, he is liable twice. [The rationale is that] at the time he took the oath that he would not eat it up, he would not be liable unless he ate the entire loaf. Thus when he took a second oath that he would not eat anything or that he would not eat the loaf, he is liable [for the latter oath,] when he eats an olive-sized portion. And when he eats the entire [loaf], he is liable for his first oath.
[When a person takes] an oath not to eat figs and afterwards, takes an oath not to eat figs and grapes, he is liable twice for [eating] figs. [The rationale is that] he included the figs which were forbidden in the first oath with grapes that were permitted. Since the second oath took effect with regard the grapes, it also took effect with regard the figs and he becomes liable for two oaths, as we explained in Hilchot Ma'achalot Assurot. 8:6 states that although one prohibition does not take effect when an object is already prohibited, there are exceptions. One of them is when the second prohibition includes other entities that were not included in the first prohibition (issur kollel). Similarly, in this instance, since the second oath includes something which is not prohibited by the first oath (grapes), it takes effect.
[If one said: "I am taking] an oath that I will not eat eight [of this item]," "...an oath that I will not eat nine," and "...an oath that I will not eat ten," he is liable only once whether he ate eight, nine, or ten. (Yoreh De'ah 238:12), there are instances where the second oath can take effect according to the principle of issur kollel, a more inclusive prohibition.
[If one said: "I am taking] an oath that I will not eat ten," "...an oath that I will not eat nine," and "...an oath that I will not eat eight," if he eats ten, he is liable three times, one for each oath. Similarly, if he eats nine, he is liable twice. If he eats eight, he is liable once. (Yoreh De'ah 238:13) states that if the person specifies 10 specific items in his oath, he is not liable if he later reduces their number to eight, for all ten have become forbidden to him.
[The following rules apply when a person says: "I am taking] an oath that I will not eat figs," and then takes another oath that he will not eat figs and grapes together.. If he forgot, ate figs, and set aside a sacrifice, afterwards, forgot, and ate grapes, he is not liable for the grapes. [The rationale is that] this is like half the measure [for which one is liable] and one does not bring a sacrifice for half the measure.
Similar [laws apply if] one took an oath that he would not eat ten, and then took an oath that he would not eat ten and nine. 28b. See also Rashi and Tosafot who discuss the proper wording of that source. If he ate ten, separated a sacrifice, and then forgot and ate nine, this is like half the measure and one does not bring a sacrifice for half the measure. For the final oath concerned not eating nineteen.. The intent is that the second oath included the original ten, plus a second nine. In this instance as well, had he not realized his first transgression, he would have been liable twice for eating the second nine.
📊 Stacking Oaths
Separate oaths on related items create separate liabilities. An oath on a category (figs) and a second oath adding another item (figs and grapes) — both apply independently. Numerical oaths ('not eight', 'not nine') create distinct obligations based on whether numbers subsume each other.
[When a person says: "I am taking] an oath that I will not eat this large loaf if I eat this small loaf," if he forgets this stipulation when he eats the smaller loaf and afterwards willfully eats the larger [loaf], he is liable [for lashes]. 28a suggested by Rabbenu Chananel. The standard published text of the Talmud reverses the ruling. Thus in the instance stated by the Rambam, one would be exempt as the Ra'avad notes. The ruling of the Shulchan Aruch (Yoreh De'ah 239:16) follows that of the standard printed text of the Talmud. The Rambam's rationale can be explained as follows: Since the person willfully transgressed by eating the larger loaf, he is liable for lashes. The fact that he inadvertently caused the oath to take effect is not of consequence. The person is liable for lashes only when he is given a warning before transgressing. From this we see that even if a warning is given conditionally, it is effective.
If he ate the small one while he remembered the stipulation and knew that by eating it, the larger one would become forbidden and then forgot and ate the larger one while thinking that it was not forbidden yet, he is exempt. If he ate both of them unintentionally, he is exempt. [If he ate them] both willfully, he is liable, regardless of whether he ate the larger one first or last.
Similarly, if he made the two loafs dependent on each other, taking an oath saying: "[I am taking] an oath that I will not eat one of these [loaves] if I eat the other." If he forgot the stipulation and ate one of them and then willfully ate the other, he is liable.
[When a person says: "I am taking] an oath that I will eat this loaf today," and the day passes without him eating it, should he have acted unintentionally, he must bring an adjustable guilt offering. If he acted willfully, he is not liable for lashes, because he did not perform a deed, 18:2. Note the following halachah. even though he violated [the prohibition against] taking a false oath.
Why is a person who took an oath that he ate liable for lashes [if] he did not eat and one [who took an oath] that he did not eat [liable] if he did eat, even though he did not perform a deed. Because at the time he took the oath, he was taking a false oath. If, however, a person takes an oath that he will perform [a particular activity], it is not a false oath at the time it was taken.
[The following laws apply when] a person tells a colleague: "[I am taking] an oath that I will not eat at your [home]," or [his colleague] was persistently imploring him to eat at his [home] and he refuses. If he takes an oath and says: "My oath [will take effect] if I eat at your [home]," or if he says: "There will be no oath if I do not eat at your [home],", Sh'vuot 36b. these all bring about prohibitions. [It is considered that] he took an oath that he would not eat at his [home]. If he used all of these expressions [together] and transgressed and ate, he is only liable once. 16a. One might think that the passage means that the person took an oath that he would not eat at his colleague's home. Afterwards, his colleague implored him to eat and to appease him, he took an oath that he would eat at his home. Seemingly, this resembles an oath taken in vain, for he is taking an oath to nullify the observance of a mitzvah - the fulfillment of his previous oath. For this reason, the Rambam explains that all of these expressions should be interpreted to mean that he is taking an oath not to eat. Only one of them takes effect, because one oath does not take effect when an object is already forbidden.
🔗 Linked Loaves
When oaths are mutually dependent (eating the small loaf triggers the large), eating the small willfully while forgetting the link vs. remembering it yields different liability. Positive oaths ('I will eat this loaf today') — if unfulfilled — incur lashes for the positive violation, not a korban.
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🎓 Key Principles
Chapter 4
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Eating Has a Threshold Most oath-eating violations require an olive-sized portion. 'Tasting' oaths operate without any minimum quantity.
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Numbers Create Independent Oaths Swearing not to eat eight, then not to eat nine, then not to eat ten — each oath functions independently and carries distinct liability.
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Linked Oath Logic When two oaths are conditional on each other, the willfulness or inadvertence of the triggering act determines liability for both.
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Positive Oath Violations Failing to fulfill a positive oath ('I will eat this loaf') results in lashes — not a korban — because the violation is defined by inaction at day's end.