אורח חיים תר״חOrach Chayim 608

Se’if 1א׳

אוֹכְלִים וּמַפְסִיקִים קֹדֶם בֵּין הַשְּׁמָשׁוֹת שֶׁצָּרִיךְ לְהוֹסִיף מֵחֹל עַל הַקֹּדֶשׁ; וְתוֹסֶפֶת זֶה אֵין לוֹ שִׁעוּר, אֶלָּא קֹדֶם בֵּין הַשְּׁמָשׁוֹת, שֶׁזְּמַנּוֹ אֶלֶף וְת"ק אַמָּה קֹדֶם הַלַּיְלָה, צָרִיךְ לְהוֹסִיף מֵחֹל עַל הַקֹּדֶשׁ מְעַט אוֹ הַרְבֵּה.

The Order of the Concluding Meal and in it is 4 paragraphs. We eat and stop before Bein Hashamashos (Twilight). Due to it is necessary to add from the weekday to the Holy (day of Yom Kippur). And this added time does not have a measure (i.e. a Halachic minimum requirement). Rather prior to Twilight whose time is (the amount time to walk) 1500 amah (amah is a halachic measure between 48-60 centimeters) before the Night, it is necessary to add from the weekday to the Holy day, a little or a lot.

Se’if 2ב׳

נָשִׁים שֶׁאוֹכְלוֹת וְשׁוֹתוֹת עַד שֶׁחָשְׁכָה, וְהֵן אֵינָן יוֹדְעוֹת שֶׁמִּצְוָה לְהוֹסִיף מֵחֹל עַל הַקֹּדֶשׁ, אֵין מְמַחִין בְּיָדָן כְּדֵי שֶׁלֹּא יָבוֹאוּ לַעֲשׂוֹת בְּזָדוֹן. הַגָּה: וְהוּא הַדִּין בְּכָל דְּבַר אִסּוּר אַמְרִינָן: מוּטָב שֶׁיִּהְיוּ שׁוֹגְגִין וְלֹא יִהְיוּ מְזִידִין; וְדַוְקָא שֶׁאֵינוֹ מְפֹרָשׁ בַּתּוֹרָה, אַף עַל פִּי שֶׁהוּא דְּאוֹרַיְתָא; אֲבָל אִם מְפֹרָשׁ בַּתּוֹרָה, מוֹחִין בְּיָדָן (רַ"ן פ"ד דְּבֵיצָה וְרֹא"שׁ בְּשֵׁם הָעִטּוּר). וְאִם יוֹדֵעַ שֶׁאֵין דְּבָרָיו נִשְׁמָעִין, לֹא יֹאמַר בָּרַבִּים לְהוֹכִיחָן, רַק פַּעַם אַחַת, אֲבָל לֹא יַרְבֶּה בְּתוֹכָחוֹת מֵאַחַר שֶׁיּוֹדֵעַ שֶׁלֹּא יִשְׁמְעוּ אֵלָיו; אֲבָל בְּיָחִיד חַיָּב לְהוֹכִיחוֹ עַד שֶׁיַּכֶּנּוּ אוֹ יְקַלְּלֶנּוּ. (רַ"ן סוֹף פֶּרֶק הבע"י).

Women who eat and drink until dark, and they do not know it is a command to add from the weekday to the Holy day, we do not contest their actions in order that they do not so willingly. Rema: Similarly, every matter it is better a prohibition done negligently and not done purposefully. This is specifically when it is not explicit in the Torah even though it is a Torah command. But if it is explicit in the Torah, we do protest in the (transgressor's) action [Ran Chapter 4 of Beitzah, and Rosh in the name of the Ittur]. And if it is known that his words will not be listened to, do not say publically to rebuke except once, but don't increase rebuke since he knows that they won't listen to him. But privately, a person is obligated to rebuke until hit or cursed (by the transgressor) [Ran end of Chapter].

Se’if 3ג׳

אִם הִפְסִיק מֵאֲכִילָתוֹ בְּעוֹד הַיּוֹם גָּדוֹל, יָכוֹל לַחֲזֹר וְלֶאֱכֹל כָּל זְמַן שֶׁלֹּא קִבֵּל עָלָיו הַתַּעֲנִית. הַגָּה: וְעַיֵּן לְעֵיל סִימָן תקנ"ג דְּאִם קִבֵּל בַּלֵּב לֹא הָוֵי קַבָּלָה.

3. If one breaks from his eating when still there is much of the day, he is able to return and eat, as long that he did accept the fast. Rema: And see prior in Siman 553 that he if accepted (only) in his heart, it is not an acceptance.