ולא יכלו החרטמים לעמד לפני משה מפני השחין ... ויחזק ד' את לב פרעה
Concerning the previous plagues, the Torah writes that Pharaoh personally strengthened/hardened his heart. Regarding makkas shechin, boils, the Torah attests, Va’yichazek Hashem es lev Pharaoh, “Hashem strengthened Pharaoh’s heart.” What had transpired to catalyze this change? Ramban explains that as long as he was surrounded by his magicians, Pharaoh was ashamed to concede the truth: he had lost control. Hashem was stronger. The Jewish people should be permitted to leave. Pharaoh the rasha, wicked, would never allow anyone to observe him in a moment of weakness. It might denigrate their perception of him as a deity. When Egypt was stricken…