The Rambam, in Hilkhot Sefer Torah (chapter 8), lists all the paragraph breaks that must be made in the text of the Sefer Torah. These include\ both petuchot – full-line breaks, where a piece of text begins on the line below the preceding text – and setumot – empty space on a single line, where the text begins on the same line as the preceding text, after an empty space. His list of the paragraph breaks in Parashat Vaera is subject to a good deal of controversy, due to variant editions of the Rambam’s wording. According to some editions, the Rambam includes a paragraph break – specifically, a setuma – after God’s command to Moshe to warn Pharaoh about the impending plague of frogs (after the words, “ya’alu ha-tzefard’im” – 7:29). This command is followed by God’s subsequent command that Aharon should raise his staff to bring the plague (8:1), and according to some editions of the Rambam’s list, this second command begins a new paragraph in the Torah. The Kesef Mishneh cites those who claim that this verse does not actually belong in the Rambam’s list, and it was added due to a copyist’s error. However, the Kesef Mishneh accepts what appears to have been the standard edition of the Mishneh Torah, which included this verse in the Rambam’s list. He notes that in the Ixar edition of the Torah, this verse indeed begins a new paragraph.
This controversy affects another verse in Sefer Shemot, as well. The Rambam concludes his list of the paragraph breaks in Sefer Shemot by noting that this book includes a total of ninety-five setumot. If we omit the reference to the aforementioned verse in Parashat Vaera, then we are left with only ninety-four setumot. As such, those who follow the edition that omits this reference are compelled to alter the Rambam’s text elsewhere in this passage. Namely, they claim that the Rambam lists two setumot in the final of the Ten Commandments. The Rambam lists “lo tachmod” (“you shall not covet”) as one of the verses that begin after a setuma paragraph break, but according to this view, the Rambam actually lists “lo tachmod” twice – referring to the two verses that comprise the tenth of the Aseret Ha-dibberot, both of which begin with the words “lo tachmod.” Meaning, according to those who maintain that God’s command to Aharon to produce the plague of frogs does not begin a new paragraph, the “missing” setuma is found at the end of the Ten Commandments, as in their view, both verses of the final commandment constitute independent paragraphs.
Common practice follows the view disapprovingly cited by the Kesef Mishneh, according to which God’s command to Aharon in Parashat Vaera does not begin a new paragraph, whereas each verse of the command of “lo tachmod” constitutes a separate paragraph.
Rav Tzvi Hersh Grodzynsky, in his Mikra’ei Kodesh (Parashat Vaera), suggests drawing proof to this view from the presentation of the Ten Commandments in Sefer Devarim (chapter 5). There, as in Sefer Shemot, the commandment of “lo tachmod” consists of two imperative statements (though the second begins with “lo tit’aveh,” as opposed to “lo tachmod’), and Rav Grodzynsky notes that both imperative statements constitute independent paragraphs. It thus stands to reason that the parallel verses in the first version of the Ten Commandments, in Sefer Shemot, also follow this format, with each comprising a separate paragraph. Although there are several differences between the two versions of the Ten Commandments, there are no discrepancies with regard to paragraph breaks. The only exception is that in the first version, in Sefer Shemot, the fourth commandment (“Zakhor et yom ha-Shabbat”) begins after a petucha paragraph break, on the line below the end of the third commandment, whereas in Sefer Devarim, the fourth commandment begins with a setuma. However, there are no instances of a paragraph break in one version of the Ten Commandments at a place where there is no paragraph break at all in the other version. It thus seems reasonable to assume that just as “lo tachmod” comprises two separate paragraphs in Sefer Devarim, it likewise comprises two paragraphs in Sefer Shemot. By extension, then, God’s command to Aharon to bring the plague of frogs does not begin a new paragraph.