וַיִּקְח֞וּ אֶת־פִּ֣יחַ הַכִּבְשָׁ֗ן וַיַּֽעַמְדוּ֙ לִפְנֵ֣י פַרְעֹ֔ה וַיִּזְרֹ֥ק אֹת֛וֹ מֹשֶׁ֖ה הַשָּׁמָ֑יְמָה וַיְהִ֗י שְׁחִין֙ אֲבַעְבֻּעֹ֔ת פֹּרֵ֕חַ בָּאָדָ֖ם וּבַבְּהֵמָֽה׃
And they took soot of the furnace, and stood before Pharaoh; and Moses threw it up heavenward; and it became a boil breaking forth with blains upon man and upon beast.
Read kabbalistic (mystical) interpretation of Exodus 9:10: and classical mystical sources.