8:5ח׳:ה׳
1 א

בעשירי נראו ראשי ההרים. זֶה אָב, שֶׁהוּא עֲשִׂירִי לְמַרְחֶשְׁוָן שֶׁהִתְחִיל הַגֶּשֶׁם. וְאִם תֹּאמַר הוּא אֱלוּל, וַעֲשִׂירִי לְכִסְלֵו שֶׁפָּסַק הַגֶּשֶׁם, כְּשֵׁם שֶׁאַתָּה אוֹמֵר בַּחֹדֶשׁ הַשְּׁבִיעִי סִיוָן, וְהוּא שְׁבִיעִי לַהַפְסָקָה – אִי אֶפְשָׁר לוֹמַר כֵּן, עַל כָּרְחֲךָ שְׁבִיעִי אִי אַתָּה מוֹנֶה אֶלָּא לַהַפְסָקָה, שֶׁהֲרֵי לֹא כָלוּ אַרְבָּעִים יוֹם שֶׁל יְרִידַת גְּשָׁמִים, וּמֵאָה וַחֲמִשִּׁים שֶׁל תִּגְבֹּרֶת הַמַּיִם עַד אֶחָד בְּסִיוָן; וְאִם אַתָּה אוֹמֵר שְׁבִיעִי לַיְרִידָה, אֵין זֶה סִיוָן, וְהָעֲשִׂירִי אִי אֶפְשָׁר לִמְנוֹת אֶלָּא לַיְרִידָה, שֶׁאִם אַתָּה אוֹמֵר לַהַפְסָקָה וְהוּא אֱלוּל, אִי אַתָּה מוֹצֵא בָּרִאשׁוֹן בְּאֶחָד לַחֹדֶשׁ חָרְבוּ הַמַּיִם מֵעַל הָאָרֶץ; שֶׁהֲרֵי מִקֵּץ אַרְבָּעִים יוֹם מִשֶׁנִּרְאוּ רָאשֵׁי הֶהָרִים שִׁלַּח אֶת הָעוֹרֵב וְכ"א יוֹם הוֹחִיל בִּשְׁלִיחוּת הַיּוֹנָה, הֲרֵי שִׁשִּׁים יוֹם מִשֶּׁנִּרְאוּ רָאשֵׁי הֶהָרִים עַד שֶׁחָרְבוּ פְנֵי הָאֲדָמָה. וְאִם תֹּאמַר בֶּאֱלוּל נִרְאוּ, נִמְצָא שֶׁחָרְבוּ בְּמַרְחֶשְׁוָן וְהוּא קוֹרֵא אוֹתוֹ רִאשׁוֹן, וְאֵין זֶה אֶלָּא תִּשְׁרֵי, שֶׁהוּא רִאשׁוֹן לִבְרִיאַת עוֹלָם, וְלְרַבִּי יְהוֹשֻׁעַ הוּא נִיסָן:

בעשירי וגו' נראו ראשי ההרים IN THE TENTH MONTH … WERE THE TOPS OF THE MOUNTAINS SEEN —This was Ab which is the tenth from Marcheshvan when the rain began. If, however, you say that it means Elul, the tenth month from Kislev in which the rain stopped, just as you said (see Rashi on verse 4) that “in the seventh month” means Sivan which was the seventh month after the rain stopped, then I reply that it is impossible to argue so. For you must needs admit that the “seventh” month when the Ark rested can only be counted from the time when the rain stopped, since the 40 days during which the rain fell and the 150 days during which the waters prevailed did not terminate until the first day of Sivan, and if you say that it means the seventh after the rain began to fall, this would not be Sivan. The “tenth month”, however, when the tops of the mountains became visible cannot possibly be counted except from the time the rain began to fall, for if you say that it must be calculated from the time when it stopped, which would be Elul, you would not then find that “in the first month, on the first day of the month the waters dried up from off the earth” (Genesis 8:13). For it was only at the end of 40 days after the tops of the mountains were visible that he sent forth the raven (Genesis 8:6), and he waited periods amounting altogether to 21 days during which he was sending forth the dove, making altogether 60 days from when the tops of the mountains became visible until when the face of the earth became dry; if, therefore, you say that it was in Elul that they were seen, it would follow that the earth became dry in Marcheshvan (60 days after Elul). But it (Scripture) calls it (the month when the waters were dried up; Genesis 5:13) the first month, and that can only be Tishri which is the first month reckoning according to the creation of the world — or according to R. Joshua, it would be Nisan (Genesis Rabbah 30:6).