Shulchan Aruch (Yoreh De’ah 210:2) rules that if a person makes an oath in a dream, the oath has no validity, and it does not have to be nullified. However, there are those who say that ten men should be assembled to nullify the oath, and it is appropriate to consider this opinion. The Sha”ch comments that even if in the dream itself the dreamer sees that ten people nullified the oath, this is not adequate, because we have to suspect that the nullification was the part of the dream that was worthless, and that the oath is still valid.
Pischei Teshuva cites a case which was brought before the Chasam Sofer. A person saw in his dream that he took an oath not to eat cooked matzah during Pesach that year. According to the second opinion of the Shulchan Aruch, the oath is binding. The question was does the dreamer have to consider the stipulation of Pesach “that year” as a part of the dream which was null, and he was therefore prohibited from cooked matzah every year, or could it be that he was prohibited only that year’s Pesach alone.
The Chasam Sofer answered that the dreamer was only prohibited from eating cooked matzah that year alone. He reasoned that if we were to treat the phrase “that year” as meaningless, perhaps we might interpret the word “Pesach” or “matzah” as worthless terms. This would put into question whether he was prohibited from cooked matzah all year long (if we were to disregard the limitation of Pesach), or that he could not have matzah in any shape or form (if the word cooked were to be discounted). Rather, the only element of an oath in a dream which can be treated as superfluous is an independent aspect of the oath, such as whether the people who nullified it in the dream itself were meaningful. However, any aspect of the oath which describes the oath itself cannot be removed.
