Shall become blood. — The verb is repeated in the Hebrew, which intensifies the assertion. The English equivalent of the phrase used would be, “shall assuredly become.” The signs were, no doubt, selected primarily for facility of exhibition; but they may also have been intended to be significant. The change of a rod into a serpent showed that a feeble implement might become a power to chastise and to destroy. That of a healthy into a leprous hand, and the reverse, indicated that Moses’s mission was both to punish and to save; while the change of water into blood suggested — albeit vaguely — the conversion of that peace and prosperity, which Egypt was enjoying, into calamity, suffering, and bloodshed.
Related Commentaries of Exodus 4:9
Exodus 4:9
9 And it shall come to pass, if they will not believe also these two signs, neither hearken unto thy voice, that thou shalt take of the water of the river, and pour it upon the dry land: and the water which thou takest out of the river shall become blood upon the dry land.