וַיְהִי־ק֕וֹל מֵעַ֕ל לָרָקִ֖יעַ אֲשֶׁ֣ר עַל־רֹאשָׁ֑ם בְּעָמְדָ֖ם תְּרַפֶּ֥ינָה כַנְפֵיהֶֽן׃
At may isang tinig mula sa itaas ng kalawakan na nasa ibabaw ng kanilang mga ulo; kapag sila ay tumitigil, ibinababa nila ang kanilang mga pakpak.
Kitzur Ba'al HaTurim
From above the firmament: There are two [places this appears] according to the tradition: here and the other is (Ezekiel 1:25), "and there was a voice from above the firmament," in the chariot [apparition] of Ezekiel. And in the same way that we don't teach about 'the story of creation' in public, so [too] do we not teach about 'the story of the chariot' [in public].
Rashi
when they would stand, they would let down their wings [and cease] from making a sound be heard, and Jonathan rendered: when they would stand, they would silence their wings because of the speech, [i.e., because of] the speech of the Omnipresent emanating from above their heads, to let the prophets hear His mission, as he [Ezekiel] concludes (verse 25): “And there was a voice, etc.” The Midrash Aggadah (Gen. Rabbah 65:11) states: “When they would stop praising [God] so that Israel would praise first.”