Exodus 7:13

He hardened Pharaoh's heart] This should be 'Pharaoh's heart was hardened,' as in RV. The Heb. is the same here as in Exodus 7:22 : see on Exodus 4:21.

14-25. The First Plague:—The Water of the Nile turned into Blood.

The Nile was regarded as a god to whom worship and sacrifice were offered. The defilement of its waters, therefore, was a severe blow to the religious prejudices of the Egyptians. It was also a great calamity, as the Nile was the source of all the fertility of Egypt, and its fish were largely used for food, some kinds being regarded as sacred.