Exodus 7:20

7:20 Moses and Aaron did so, just as the Lord had commanded. Moses raised the staff and struck the water that was in the Nile right before the eyes of Pharaoh and his servants, and all the water that was in the Nile was turned to blood.

Exodus 8:26

8:26 But Moses said, “That would not be the right thing to do, for the sacrifices we make to the Lord our God would be an abomination to the Egyptians. If we make sacrifices that are an abomination to the Egyptians right before their eyes, will they not stone us?