The Gemara rules that the Tochacha portions in Leviticus and Deuteronomy must be read by a single reader without interruption, and discusses why — so that the curses not be 'separated' but remain bound together as a unit.
בְּתַעֲנִיּוֹת בְּרָכוֹת וּקְלָלוֹת, וְאֵין מַפְסִיקִין בַּקְּלָלוֹת. מְנָא הָנֵי מִילֵּי? אָמַר רַבִּי חִיָּיא בַּר גַּמָּדָא אָמַר רַבִּי אַסִּי: דְּאָמַר קְרָא ״מוּסַר ה׳ בְּנִי אַל תִּמְאָס״. רֵישׁ לָקִישׁ אָמַר: לְפִי שֶׁאֵין אוֹמְרִים בְּרָכָה עַל הַפּוּרְעָנוּת: אֶלָּא הֵיכִי עָבֵיד? תָּנָא: כְּשֶׁהוּא מַתְחִיל — מַתְחִיל בַּפָּסוּק שֶׁלִּפְנֵיהֶם, וּכְשֶׁהוּא מְסַיֵּים — מְסַיֵּים בַּפָּסוּק שֶׁלְּאַחֲרֵיהֶן. אָמַר אַבָּיֵי: לֹא שָׁנוּ אֶלָּא בִּקְלָלוֹת שֶׁבְּתוֹרַת כֹּהֲנִים, אֲבָל קְלָלוֹת שֶׁבְּמִשְׁנֵה תוֹרָה — פּוֹסֵק. מַאי טַעְמָא — הַלָּלוּ בִּלְשׁוֹן רַבִּים אֲמוּרוֹת, וּמֹשֶׁה מִפִּי הַגְּבוּרָה אֲמָרָן, וְהַלָּלוּ בִּלְשׁוֹן יָחִיד אֲמוּרוֹת, וּמֹשֶׁה מִפִּי עַצְמוֹ אֲמָרָן.
§ The mishna states: On fast days the congregation reads the portion of blessings and curses (Leviticus, chapter 16), and one may not interrupt the reading of the curses by having two different people read them. Rather, one person reads all of them. The Gemara asks: From where are these matters derived? Why does one not interrupt the reading of the curses? Rabbi Ḥiyya bar Gamda said that Rabbi Asi said: For the verse states: “My son, do not despise the chastening of the Lord, nor be weary of His correction” (Proverbs 3:11). If one makes a break in the middle of the curses, it appears as if he loathes rebuke. Reish Lakish said a different answer: It is because one does not say a blessing over a calamity. If a second person were to begin to read in the middle of the portion of the curses, the blessing upon his reading would be considered a blessing over a calamity. Rather, what does one do? It is taught in a baraita: When one begins the reading, one begins with the verse before the curses, and when one concludes the reading, one concludes with the verse after them. In this way, neither the blessing before the reading nor after it relates directly to verses of calamity. Abaye said: They taught this only with regard to the curses that are recorded in Leviticus, but with regard to the curses that are recorded in Deuteronomy, one may interrupt them by having two different people read them. What is the reason for this distinction? These curses in Leviticus are stated in the plural, and Moses pronounced them from the mouth of the Almighty. As such, they are more severe. However, these curses in Deuteronomy are stated in the singular, and Moses said them on his own, like the rest of the book of Deuteronomy. They are therefore less harsh and may be interrupted.