וַיֹּ֨אמֶר יְהוָ֜ה אֶל־מֹשֶׁה נְטֵ֤ה אֶת־יָֽדְךָ֙ עַל־הַשָּׁמַ֔יִם וִיהִ֥י בָרָ֖ד בְּכָל־אֶ֣רֶץ מִצְרָ֑יִם עַל־הָאָדָ֣ם וְעַל־הַבְּהֵמָ֗ה וְעַ֛ל כָּל־עֵ֥שֶׂב הַשָּׂדֶ֖ה בְּאֶ֥רֶץ מִצְרָֽיִם׃
Kemudian Yang Mahakekal berfirman kepada Musa, “Ulurkanlah tanganmu ke arah langit, supaya turun hujan es di seluruh tanah Mesir, menimpa manusia, ternak, dan segala tumbuh-tumbuhan di padang di tanah Mesir.”
Rashi
על השמים signifies towards the heavens (i. e. על is the equivalent of אל). A Midrashic comment is that the Holy One, blessed be He, raised Moses high above the heavens see Midrash Tanchuma, Vaera 15).
Siftei Chakhamim
Over the heavens. I.e., at first Moshe had control only over matters on earth. Now Hashem lifted Moshe up and gave him control over matters in heaven, and Moshe brought a plague from heaven.