אורח חיים קל״זOrach Chayim 137

Se’if 1א׳

בְּיוֹם שֶׁקּוֹרִין ג', אֵין קוֹרִין פָּחוֹת מִי' פְּסוּקִים; וַיְדַבֵּר עוֹלֶה מִן הַמִּנְיָן. וְאִי סָלִיק עִנְיָנָא בְּבָצִיר מִי' פְּסוּקִים, כְּגוֹן פָּרָשַׁת עֲמָלֵק (שְׁמוֹת יז, ח טז) שֶׁאֵין בָּהּ אֶלָּא ט' פְּסוּקִים, שַׁפִּיר דָּמִי.

How Many Verses Must Be Read For Each Aliyah. Containing 6 Se'ifim: On a day that 3 [people] read, we do not read less than 10 verses. [The frequent short introductory verse] "And [the Lord] spoke..." is included in the count [of verses]. And if the topic ends in less than 10 verses, for example the parsha of Amalek [Exodus 17:8] which has only 9 verses, it is acceptable.

Se’if 2ב׳

אֵין קוֹרִין עִם כָּל אֶחָד פָּחוֹת מִג' פְּסוּקִים, שְׁנַיִם קוֹרִין ג' ג', וְאֶחָד קוֹרֵא ד'; וְאֵיזֶה מֵהֶם שֶׁקּוֹרֵא ד' הֲרֵי זֶה מְשֻׁבָּח.

Each person does not read less than 3 verses. Two read 3 each, and one reads 4, and whichever one of them it is who reads 4, behold this one is praiseworthy.

Se’if 3ג׳

אִם דִּלֵּג פָּסוּק אֶחָד וְלֹא קְרָאוֹ, אִם הוּא בְּמִנְחָה בְּשַׁבָּת אוֹ בְּב' וְה' וְקָרָא יוֹ"ד פְּסוּקִים בְּלֹא פָּסוּק הַמְדֻלָּג, אֵינוֹ חוֹזֵר; וְאִם לָאו, חוֹזֵר. אֲבָל בְּשַׁבָּת, אֲפִלּוּ דִּלֵּג פָּסוּק אֶחָד חוֹזֵר וְקוֹרֵא, וַאֲפִלּוּ אַחַר שֶׁהֶחֱזִיר אֶת הַתּוֹרָה וְאָמַר קַדִּישׁ חוֹזֵר וְקוֹרֵא הוּא וּשְׁנַיִם עִמּוֹ; וַאֲפִלּוּ הִפְטִיר וְהִתְפַּלֵּל מוּסָף, חוֹזֵר וְקוֹרֵא. פָּרָשִׁיּוֹת הַמּוֹעֲדִים דִּינָם כְּמוֹ מִנְחָה בְּשַׁבָּת וְשֵׁנִי וַחֲמִישִׁי, לְפִי שֶׁכְּבָר קָרְאוּ הַפָּרָשִׁיּוֹת בַּשַּׁבָּתוֹת שֶׁלָּהֶן.

If one skipped a verse and didn't read it - if it was Mincha on Shabbos, or a Monday or Thursday, and they read 10 verses besides for the skipped verse, they do not need to go back [and repeat the reading], but if not, then they must go back. But if it was [the] Shabbos [morning reading], then even if he skipped one verse, he must go back and read again; even if they already returned the Torah [to the ark] and they said Kaddish, he must go back and read - the skipped verse and two others; and even if they [already] read the Haftarah (the reading from the Prophets) and prayed Mussaf, he must go back and read again. The Torah readings on the Festivals (their laws) are similar to Shabbos Mincha, Monday, and Thursday, since they already read those readings on their [respective] Shabbos.