פירוש על יחזקאל 38:22

and great hailstones Hailstones that glisten like precious stones named גָּבִישּׁ, crystal, as the matter is stated (Job 28:18): “Coral and crystal (וְגָּבִישּׁ).” Our Sages said (Ber. 54b): עַל גַב אִישּׁ: Hailstones that started to fall on Egypt, and stood in the air over the man (עַל גַב אִישּׁ), Moses, who prayed that they not fall, as the matter that is stated (Exod. 9:33), לֹא נִתַּךְ אַרְצָה “[it] did not reach the ground.”