Multi-day water fast on Shabbos
Question:
I have been suffering for the last few years from an extremely bothersome chronic condition. After much research and experimentation, I want to try doing a multi-day water fast (only water, no food or other beverages whatsoever) for a period of 10-12 days.
To eat anything on Shabbos would effectively bring the body’s fasting process to an immediate end (making it a 6 day fast, if I start right after Shabbos), and it would be pointless to resume the fast after Shabbos. Hence my question whether I would be allowed in this case to continue fasting through Shabbos?
Answer:
In your case, you may do this fast. However, then you would not be able to fulfill the mitzvah of kiddush and lechem mishnah. However, the Biblical aspect of kiddush would still be fulfilled during davening. You should also, if possible, hear kiddush from someone else. If not possible, you should at least say Vayechulu at night.
You should also try to hear the bracha of Hamotzi over lechem mishna from someone else.
Sources:
להתענות – אדה״ז רפח, ב.
קידוש בתפלה – ראה אדה״ז רפט, ג. שע״ת ערב, ב. משנ״ב רפט, י. אג״מ או״ח ב, כו ד״ה ובדבר.
וי״א שיוצא גם ללא סעודה – ועכ״פ בשוגג או באונס, ראה אצלנו 27829:
ויכולו – ראה שו״ת מנח״י ח, ל, ה.
לחם משנה – שי״א שהוא כמו בקידוש שהמצוה בשמיעה לחוד, ראה הליכות שלמה ניסן ט בדבר הלכה עט. שאלת רב ב ע׳ שיט בשם הגרח״ק, ובביאור דעתו – אליבא דהלכתא נ ע׳ לא. אבל בכ״מ מוכח שהחיוב לאכול.
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