And in this way we find in the holy book "Degel Machaneh Ephraim" (Exodus, Parashat Va'era) and this is his language: "Pharaoh's heart was heavy, he refused to let the people go" (Exodus 7:14) – it is noteworthy that this phrase is written only in reference to the first plague, which was blood. Also, the heaviness of his heart was not yet so well known. And I heard in the name of my father-in-law, the renowned Rabbi Lipa of the holy community of Kamenetz-Podolsk, and it seems to me that I later saw this written in the Midrash, that "Pharaoh's heart was heavy," meaning that Pharaoh's heart turned and became heavy. Up to here.

And it is known that from Him no evil comes, God forbid, and any evil that befalls a person, God forbid, the sin itself chastises him, and the recompense of his hands is dealt to him, "Your own wickedness will punish you" (Jeremiah 2:19). "We melt away in the hand of our iniquities" (Isaiah 64:6). And therefore, surely the punishment is akin to the defect and evil he committed. And this can be said to be the reason that the first plague was the plague of blood, because it was related to his defect and sin, that his evil was that his heart became heavy, and from this sin a destroyer was born, and from this came the plague of blood upon him, which is akin to heaviness, as it involves an excess of blood, and it is filled with blood. End of quote.