הַאֲזִינוּ הַשָּׁמַיִם וַאֲדַבֵּרָה וְתִשְׁמַע הָאָרֶץ אִמְרֵי פִי
Give ear, ye heavens, and I will speak; and let the earth hear the words of my mouth (Deuteronomy 32:1)
Our master explained this verse in accord with the commentators on the פיוט of the ימים נוראים "A man may prepare the thoughts in his mind, but the power of speech comes from the L-rd" (לְאָדָם מַעַרְכֵי לֵב וּמֵה' מַעֲנֵה לָשׁוֹן) who say that if listeners, wishing to learn how to do what is good, focus their minds and hearts on the Eternal to hear instruction and wisdom from the one who reproves them, then the Eternal will enhance the eloquence of the speaker who will deliver an upright discourse sweeter than honey and the honeycomb that will draw the hearts of those listening toward him. However, if they come hear his discourse, only for enjoyment and to take pleasure in the speaker's eloquence and intelligence, but they are not sincere and they do not want to hear reproof and instruction to improve their conduct, then the Eternal will not give the speaker (Isaiah 50:4) "the tongue of those who are taught" (לשון לימודים), so that the listeners will not gain their desire to enjoy his pleasant discourse and so that their guilt for rejecting moral instruction should be mitigated. So did Yishayahu the prophet say (Isaiah 29:13-14): "Because this people draw near with their mouth and honor me with their lips," for they came close to hear his beautiful oratory and his lofty visions. But "their hearts are far from me" and they did not turn to hearken to him. That is why "the wisdom of their wise men shall perish and the discernment of their discerning men shall be hid." so that they will not be able to accomplish their goal.
Now the letter "ה" in the word "וַאֲדַבֵּרָה" is added, as the grammarians know, to adorn the language. And Moshe was, from his youth, slow of speech and of a slow tongue; his speech was like that of stammerers and was unpleasant to hear. But if the Eternal placed words in his mouth and the Divine Presence was speaking from his throat, he then spoke words of beauty and his tongue was that "of those who are taught." As the Midrash in פרשת דברים says about him "The tree of life heals speech." This then is the meaning of the verse: "Give ear, O heavens" (הַאֲזִינוּ הַשָּׁמַיִם). If those who approach the one who gives reproof are dedicated toward heaven, because they wish to turn away from evil and to improve their conduct, and it is called "giving ear" (הַאֲזִינוּ) when one listens to the words of the reprover with the intention of acting accordingly, then "I will speak" (וַאֲדַבֵּרָה) with a pure speech, with the perfection of beauty," which is represented by the extra "ה" Alternatively, the "ה" may symbolize the Divine Presence that speaks from his throat. But if "the earth will hear" (וְתִשְׁמַע הָאָרֶץ), that is if they come to satisfy the desire of their heart to hear the smooth words of eloquent speakers, which is referred to as "hearing" (שמיעה) and not "giving ear" (האזנה), then what they will hear will be the "words of my mouth" (אִמְרֵי פִי), because I am slow of speech and of uncircumcised lips.
יַעֲרֹף כַּמָּטָר לִקְחִי תִּזַּל כַּטַּל אִמְרָתִי כִּשְׂעִירִם עֲלֵי דֶשֶׁא וְכִרְבִיבִים עֲלֵי עֵשֶׂב
My doctrine shall drop as the rain, my speech shall distil as the dew; as the small rain upon the tender grass, and as the showers upon the herb. (Deuteronomy 32:2)
See what we wrote in the name of our master in פרשת דברים that if one offers reproof to the people by relying on what is written in the Torah and does not simply offer reproof based on his own opinions, he will be well received by his audience even if he speaks sternly. But it will not be so if he will speak what he has made up from his own heart. When he offers reproof from his own heart, he should be careful to speak gently, words of pleasantness, to draw the hearts of his audience toward him. And this is what is meant by "may my teaching drop as rain" (יַעֲרֹף כַּמָּטָר לִקְחִי). Moshe will be able to speak sternly to them like a strong rain that buffets the ground if he speaks words of reproof that are taken ("לִקְחִי") from a holy place, the wellspring of the Torah. However, when Moshe speaks his own words ("אִמְרָתִי"), they should be spoken gently and slowly ("תִּזַּל כַּטַּל")
A second rule for one who offers reproof is that it is appropriate to speak sternly only to a large gathering. But if one is speaking directly to an individual he should speak elliptically and gently in order not to humiliate the individual to whom one is offering reproof. And see Rashi who explains "שְׂעִירִם" as a stormy wind and "רְבִיבִים" as rain drops; "deshe" is a general term encompassing all the folliage that covers the land, and "עֵשֶׂב" is a term for each individual type of vegetation. That is why the noun "שְׂעִירִם," representing a harsher form of reproof is coupled with "עֲלֵי עֵשֶׂב" corresponding to a harsh reproof to all the people as a group, while "רְבִיבִים", representing a gentle reproof, is coupled with "עֲלֵי עֵשֶׂב," indicating that it is directed toward a single individual.
שִׁחֵת לוֹ לֹא בָּנָיו מוּמָם דּוֹר עִקֵּשׁ וּפְתַלְתֹּל
Is corruption His? No; His children's is the blemish; a generation crooked and perverse. (Deuteronomy 32:5)
Our master said that if a father has been brought up according to the precepts of the Torah, but then becomes corrupt in his conduct, he is nevertheless disposed to return to the Eternal in the moment of his distress or in the days of repentance, because he knows that he has sinned against the Eternal. He will therefore quickly resolve to repent and repair his wrongful conduct. This is the meaning of the words: "Is corruption his?" (שִׁחֵת לוֹ). The Scripture responds: "No" (לֹא); his guilt is not considered to be very great, because he will undoubtedly repent. But "his children's is the blemish" (בָּנָיו מוּמָם). If his children have grown up being accustomed to transgress, their sins are considered as a hereditary blemish that cannot be removed until they perish, because they are "a generation crooked and perverse" (דּוֹר עִקֵּשׁ וּפְתַלְתֹּל) and they will never repent.