Classical material not listed by Torah Temimah under this passuk (EXTRA).
Core Text — EXTRA
וַיַּֽעֲשׂוּ־כֵ֛ן חַרְטֻמֵּ֥י מִצְרַ֖יִם בְּלָטֵיהֶ֑ם וַיֶּחֱזַ֤ק לֵב־פַּרְעֹה֙ וְלֹא־שָׁמַ֣ע אֲלֵהֶ֔ם כַּאֲשֶׁ֖ר דִּבֶּ֥ר יְהֹוָֽה׃
English: “And they did so” — \ldots they added to the plague.