וְהַחִטָּ֥ה וְהַכֻּסֶּ֖מֶת לֹ֣א נֻכּ֑וּ כִּ֥י אֲפִילֹ֖ת הֵֽנָּה׃
그러나 밀과 나맥은 자라지 아니한고로 상하지 아니하였더라
Rashi on Exodus
כי אפילת הנה means FOR THEY WERE LATE in growing and they were still soft and able to resist the blow of anything hard. It is true that it is stated, (v. 25) “and every herb of the field did the hail smite”, but one must explain the real meaning of that verse as referring to herbs that stood on their stalks and were therefore liable to be broken by the hail. In the Midrash of Rabbi Tanchuma 2:2:16 some of our Rabbis differed in their explanation of this, and explained the words כי אפילת to signify that most remarkable wonders (פלאי פלאות) happened to them in that they were not smitten.
Rashbam on Exodus
לא נוכו, to inform us that whatever the hail had not destroyed would be destroyed by the locusts. The hail demolished everything hard, the locust everything soft.
Sforno on Exodus
והחטה והכסמת, take note of the extent of the wickedness of Pharaoh and his servants. Even though the wheat and the spelt had not yet been destroyed, and Moses had prayed for the removal of the plague of hail, and Pharaoh had observed that all the destructive forces had ceased to be active as an immediate result of Moses’ prayer, something which made plain that but for Moses’ prayer the destruction would have continued, Pharaoh heaped more sins on top of the ones already committed, so as to make the ultimate retribution he would suffer even more terrible.