סימן קנה סעיף יא

כְּשֵׁם שֶהָאִשָּׁה חוֹשֶׁשֶׁת לְוֶסֶת הַיָמִים וּלְוֶסֶת הַהַפְלְגוֹת בְּפַעַם אַחַת, כְּמוֹ כֵן חוֹשֶׁשֶׁת גַּם לְוֶסֶת הַגּוּף וּלְוֶסֶת הַמֻּרְכָּב בְּפַעַם אֶחָת. וּכְשֵׁם שֶׁוֶּסֶת הַיָּמִים וּוֶסֶת הַהַפְלָגוֹת שֶׁאֵינָן קְבוּעִין, נֶעֱקָרִין בְּפַעַם אַחַת, כְּמוֹ כֵן וֶסֶת הַגּוּף וּוֶסֶת המֻּרְכָּב, נֶעֱקָּרִין בְּפַעַם אֶחָת. וּכְשֵׁם שֶׁוֶּסֶת הַיָּמִים וּוֶסֶת הַהַפְלָגוֹת הַקְּבוּעִים אֵינָן נֶעֱקָרִין אֶלָּא בְּשָׁלֹשׁ פְּעָמִים, כָּךְ וֶסֶת הַגּוּף וּוֶסֶת הַמֻּרְכָּב הַקְּבוּעִים אֵינָן נֶעֱקָרִין אֶלָּא בְּשָׁלֹשׁ פְּעָמִים, דְּהַיְנוּ אִם הָיָה לָהּ וֶסֶת הַגּוּף גְּרִידָא, כֵּיוָן שֶׁפִּהֲקָה אַחַר כָּךְ שָׁלֹשׁ פְּעָמִים וְלֹא רָאֲתָה, שׁוּב אֵינָהּ צְרִיכָה לָחוּשׁ כַּאֲשֶׁר תְּפַהֵק. וְאִם הוּא וֶסֶת הַמֻּרְכָּב, כְּשֶׁהִגִּיעַ שָלשׁ שָׁלֹשׁ פְּעָמִים יוֹם זֶה וּפִהֲקָה וְלֹא רָאֲתָה, אָז הַוֶּסֶת נֶעְקַר. אֲבָל הַיָמִים בְּלֹא פִהוּק אוֹ פִהוּק בְּלֹא יָמִים, אֵינָן עוֹקְרִין אֶת הַוֶּסֶת הַמֻּרְכָּב, דְּבָעֵינָן עֲקִירָתוֹ דֻּמְיָא דִקְבִיעָתוֹ.

Just as a woman must be mindful of the menstrual period as indicated by the monthly date of menstruation, and by the amount of intervening days, even after a single occurrence, so, too, must she be mindful of the menses indicated by physical symptoms alone, or in combination with (equal interval perceptions) after a single occurrence. And just as the menses based on monthly perceptions, and by the number of intervening days, if they are not established (three consecutive times), are eliminated by a one-time failure to occur, so, too, the menses based on bodily symptoms alone, or in combination with one of the above, are eliminated by a one-time failure to occur. And just as the menses of monthly perceptions, and of equal interval perceptions that have been established by three occurrences, are eliminated only by three successive occurrences (to the contrary), so, too, the menses based on bodily symptoms alone, or in combination with one of the above, after being established by three occurrences, are eliminated only by three successive occurrences to the contrary. For instance, if she has established a period based only on physical symptoms, for example, if thereafter she yawned three times, and did not perceive a flow, she no longer has to be mindful when she yawns again. If it is a period based on a combination when the fixed day arrives three times, and she yawned and did not perceive any flow, then the term is eliminated. But a change of days without yawning, or a change in yawning without a change in days, do not eliminate the term established by a combination of factors, because we require that this process of its elimination be similar to the process through which it was established.

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)