הַעִידֹתִי֩ בָכֶ֨ם הַיּ֜וֹם אֶת־הַשָּׁמַ֣יִם וְאֶת־הָאָ֗רֶץ כִּֽי־אָבֹ֣ד תֹּאבֵדוּן֮ מַהֵר֒ מֵעַ֣ל הָאָ֔רֶץ אֲשֶׁ֨ר אַתֶּ֜ם עֹבְרִ֧ים אֶת־הַיַּרְדֵּ֛ן שָׁ֖מָּה לְרִשְׁתָּ֑הּ לֹֽא־תַאֲרִיכֻ֤ן יָמִים֙ עָלֶ֔יהָ כִּ֥י הִשָּׁמֵ֖ד תִּשָּׁמֵדֽוּן׃
Yo pongo hoy por testigos al cielo y á la tierra, que presto pereceréis totalmente de la tierra hacia la cual pasáis el Jordán para poseerla: no estaréis en ella largos días sin que seáis destruídos.
Rashi
העידתי בכם I CALL AS WITNESSES AGAINST YOU [THE HEAVENS AND THE EARTH] — Behold I summon them to be witnesses that I have warned you.
Chizkuni
את השמים ואת הארץ, “both heaven and earth;” Moses refers to all the stars in heaven, as well as to the permanent and unalterable phenomena that are part of the earth. [The rock of Gibraltar, the Himalayan Mountains, etc. Ed.] (Compare Ibn Ezra)
Ibn Ezra
I call as witnesses Some say [Sa‘adya Gaon on 32: 1] that the testimony of heaven and earth denotes the angels and the human race, respectively. Others say it alludes to the rains, as in, “I will make your skies like iron and your land like brass” [Leviticus 29: 19]. In my opinion, heaven and earth are called as witnesses to watch them and their children forever, because they are permanent (as in “as long as the heaven endures on the earth” [11: 21]; “Hear, O mountains, God ’s controversy” [Micah 6: 2]; and “this stone shall be a witness to us” [Joshua 24: 27]). Those people who object to this interpretation on the grounds of such verses as “heaven shall vanish away like smoke…” [Isaiah 51: 6] are vigilant in disputation, but their minds are asleep!