פּירוש אויף שמות 7:22

בלטיהם SECRET ARTS — magic formulas which they utter secretly and in a whisper. Our Rabbis stated that בלטיהם refers to the work of demons, בלהטיהם to witchcraft (Sanhedrin 67b; Exodus Rabbah 9:11).

ויעשו כן, “and the sorcerers of Pharaoh did something similar (with the aid of their witchcraft)” Where did they take water from to duplicate such a feat? Either they brought the water from outside Egypt, or they must have dug for it. Also, the fact that the Egyptians are reported to have dug for water, something reported in verse 24 also seems out of place. We do not apply the principle of the Torah reversing historical sequences within the same paragraph.

ויעשו כן חרטומי מצרים, The Egyptian sorcerers did likewise, etc. If we follow the sages in Shemot Rabbah 9,11 according to whom all the waters in Egypt were struck, where did the Egyptian sorcerers practice their art and convert water into blood? Perhaps only visible sources of water had been turned into blood, whereas subterranean water had remained in its original state. This would explain why the Torah described the Egyptians as digging for water in verse 24.

ויחזק לב פרעה AND PHARAOH’S HEART WAS HARDENED so that he said: You are doing this by witchcraft: “You are bringing straw to Afarayim”— a city that is full of straw; thus you bring sorcery to Egypt, a land that is full of sorcery (Menachot 85a; Exodus Rabbah 9:6-7).