What Does Exodus 7:20 Mean?

Moses and Aaron did as the LORD commanded. In the sight of Pharaoh and in the sight of his servants he lifted up the staff and struck the water in the Nile, and all the water in the Nile turned into blood. The execution of the plague follows the command structure precisely: Moses and Aaron act "as the LORD commanded," and the agency of "he lifted up the staff" creates the same divine-human overlap as in verse 17: "he" refers to Moses (or Aaron acting on Moses' instruction), and the act is simultaneously the human gesture and the divine power. The struck Nile turns to blood.

The "in the sight of Pharaoh and in the sight of his servants" specification ensures that the plague was publicly witnessed by the highest Egyptian authorities. Pharaoh sees it happen. His court sees it happen. There is no ambiguity about what occurred or who caused it. The same court before which the staff-Serpent sign occurred is now the witness to the Nile's transformation. The escalation from sign (court) to plague (national water system, witnessed by court) is the progression from authentication to judgment: first prove the messenger is from YHWH, then demonstrate YHWH's judgment on Egypt.

The transformation of "all the water in the Nile" is the global Nile statement, matching the specific "even in vessels of wood and stone" of verse 19. The water of the Nile's main channel turns to blood in Pharaoh's sight; the water in every container in Egypt turns to blood per verse 19. The plague is complete and verified. The evidence Pharaoh is confronted with is total: the sacred river that was his religious and economic foundation has been transformed by the same God whose message Pharaoh has been refusing. The visual is overwhelming; the theological message is unmistakable.