וְהָיָ֣ה ׀ בַּיּ֣וֹם הַה֗וּא יִשְׁרֹ֤ק יְהוָה֙ לַזְּב֔וּב אֲשֶׁ֥ר בִּקְצֵ֖ה יְאֹרֵ֣י מִצְרָ֑יִם וְלַ֨דְּבוֹרָ֔ה אֲשֶׁ֖ר בְּאֶ֥רֶץ אַשּֽׁוּר׃
And it shall come to pass in that day, That the LORD shall hiss for the fly That is in the uttermost part of the rivers of Egypt, And for the bee that is in the land of Assyria.
Rashi on Isaiah
the Lord shall whistle Shall signal them that they assemble.
Rashi on Isaiah
to the “fly” Armies as numerous as flies, will come from Egypt with Sennacherib.