Rashi: שמעו שמים והאזיני ארץ. Moses had said: האזינו השמים ... ותשמע הארץ ("let the heavens give ear, and let the earth hear"). Why, then, did [Isaiah] change around the language? Our Rabbis taught many midhroshim with regard to this in Poroshath Ha'azinu in the Sifrê (§66); but the Hakhomim disagreed with them, and said (ibid.):
The matter is not [to beexplained according to any of these midhroshim]; rather, at a time when the witnesses are coming to give testimony, if their words are consistent (מכוונין), their testimony stands, but if their words are not consistent, their testimony does not stand. If Isaiah had not come along and enjoined שמיעה upon the heavens, and האזנה upon the earth, then the heavens would have said: "When we were called to testimony in the days of Moses, as he said 'I call [heaven and earth] as witnesses today against you' [Deuteronomy 4:26], we heard only האזנה." And the earth would have said: "I was called only with the language of שמיעה." Thus, their testimony would not have been consistent. Isaiah came along, and switched around the words, such that each of them can now give testimony both with the language of שמיעה and of האזנה.כי יי דבר -- for the LORD hath spoken that you should be witnesses about the matter. And where did He speak? האזינו השמים ואדברה (Deuteronomy 32:1). Thus is taught in the Mekhilto (Pisho 21:12).
[כי יי דבר -- for the LORD hath spoken that I warned [Israel] in the days of Moses, and you [O heavens and earth] should come and hear that I am arguing with them, for they have transgressed My warning; I did not act-offensively [סָרַחְתִּי] against them, but rather I raised them and elevated them-- yet they have rebelled against me.]
