Exodus 7:15-21
The Nile turning to blood was a statement against the Egyptians for the atrocities they committed against the Hebrew babies recorded in Exodus 1. Covering up our sin will always come back to haunt us. Jesus’ blood was not meant to cover up our sin, but to acknowledge and forgive our sin. Confession and repentance brings our sin out into the open which always leads to forgiveness (1 John 1:9-10)