Moses revealed on the day he passed away
Rabbi Shimon says that the last generation that left Egypt knew everything, because Moses revealed it all to them during the forty years that they wandered in the wilderness. Rabbi Yitzchak had taught that even Moses only revealed secrets on the last day before he died, once he was given permission to reveal them. The poem that Moses delivered to the people was drawn from the Holy Spirit downwards, and he called on the name of God when he spoke.
19. Come and see, the last generation that left Egypt knew everything because Moses revealed it to them all the forty years they were in the wilderness, as I said. We learned that Rabbi Yitzchak said, Even Moses revealed it only on the day he departed from the world, as it is written, "I am a hundred and twenty years old this day" (Devarim 31:2), on the very day HE PASSED AWAY. Hence he did not speak until he was given permission as it is written, "Now therefore write this poem for yourselves" (Ibid. 19). When he did reveal, he did not say 'Give ear, Yisrael,' but, "Give ear, O heavens" (Devarim 32:1).
19. ת"ח, דָּרָא בַּתְרָאָה דְּנַפְקוּ מִמִּצְרַיִם, יָדְעוּ כֺּלָּא, דְּהָא מֺשֶׁה גַּלֵּי לוֹן כָּל אִינּוּן מ' שְׁנִין דַּהֲווֹ בְּמַדְבְּרָא, כְּמָה דַּאֲמֵינָא. תָּאנָא א"ר יִצְחָק, וְאַף מֺשֶׁה לָא גַּלֵּי דָּא, אֶלָּא בְּהַהוּא יוֹמָא דַּהֲוָה סָלִיק מִן עָלְמָא, דִּכְתִּיב בֶּן מֵאָה וְעֶשְׂרִים שָׁנָה אָנֺכִי הַיּוֹם, בְּהַהוּא יוֹמָא מַמָּשׁ, ועכ"ד לָא אָמַר, עַד דְּיָהֲבוּ לֵיהּ רְשׁוּתָא. דִּכְתִּיב, וְעַתָּה כִּתְבוּ לָכֶם אֶת הַשִּׁירָה הַזֺּאת. וְכַד גַּלֵּי, לָא אָמַר הַאֲזִינוּ יִשְׂרָאֵל, אֶלָּא הַאֲזִינוּ הַשָּׁמַיִם.
20. Rabbi Yosi said, It is written, "this poem," THAT IS, "NOW THEREFORE WRITE THIS POEM FOR YOURSELVES." Could it be called a poem? IT SHOULD HAVE SAID 'THIS TORAH.' Rabbi Yitzchak said, It is surely a poem. As a poem is drawn through the Holy Spirit from above downwards, SO these words also were drawn through the Holy Spirit from above downwards. This is why Moses spoke of a poem.
20. א"ר יוֹסֵי, כְּתִיב אֶת הַשִּׁירָה, וְכִי שִׁירָה אִקְרֵי. א"ר יִצְחָק שִׁירָה וַדַּאי, מַה שִׁירָה אִתְמַשְּׁכָא בְּרוּחַ הַקֺּדֶשׁ מֵעֵילָּא לְתַתָּא, אוֹף הָכִי מִלִּין אִלֵּין אִתְמַשְּׁכָן בְּרוּחַ הַקֺּדֶשׁ מֵעֵילָּא לְתַתָּא, ובג"כ אָמַר מֺשֶׁה שִׁירָה.
21. Come and see all that Moses has spoken and called to the high ones before he uttered a word, as it is written, "Give ear, O heavens." "My doctrine shall drop as the rain..." (Ibid. 2). Why all that? Because "I will call on the name of Hashem" (Ibid. 3). Before he said that, he caused all the worlds to tremble.
21. ת"ח, כּוּלֵי הַאי אָמַר מֺשֶׁה, וְקָרָא לְעִלָּאִין, עַד לָא יֵימָּא מִלָּה, דִּכְתִּיב הַאֲזִינוּ הַשָּׁמַיִם. יַעֲרוֹף כַּמָּטָר וְגוֹ.' וְכָל כַּךְ לָמָּה. מִשּׁוּם כִּי שֵׁם יְיָ' אֶקְרָא. עַד דְּיֵימָּא מִלָּה, אַרְעִישׁ כֻּלְּהוּ עָלְמִין.
22. We learned that when Moses said, "Give ear, O heavens, and I will speak," the worlds shook. A voice resounded saying, Moses, Moses, why are you shaking the whole world? You are human, shall the world shake because of you? He opened and said, "I will call on the name of Hashem." At that moment they became silent and listened to his words.
22. תָּאנָא בְּהַהִיא שַׁעֲתָא דְּאָמַר מֺשֶׁה הַאֲזִינוּ הַשָּׁמַיִם וַאֲדַבֵּרָה, אִתְרְגִּישׁוּ עָלְמִין. נָפַק קָלָא וְאָמַר, מֺשֶׁה מֺשֶׁה, אֲמַאי אַתְּ מַרְעִישׁ עָלְמָא כֺּלָּא. אַתְּ בְּרֵיהּ דְּבַר נָשׁ, וּבְגִינָךְ אִתְרְגִּישׁ עָלְמָא. פָּתַח וְאָמַר כִּי שֵׁם יְיָ' אֶקְרָא. בְּהַהִיא שַׁעֲתָא אִשְׁתָּתָקוּ, וַאֲצִיתוּ מִלּוֹי.