John Calvin Commentary Exodus 4:8

"And it shall come to pass, if they will not believe thee, neither hearken to the voice of the first sign, that they will believe the voice of the latter sign." — Exodus 4:8 (ASV)

And it shall come to pass, if they will not believe you. In these words, God removed from Moses every reason for doubt, as if to say that he was sufficiently equipped and strengthened to overcome the people's stubbornness. Yet, filling the measure to overflowing, He afterward added a third sign, from which Moses might attain full confidence, ensuring that no further hindrance would oppose his godly desires.

This also is remarkable evidence of God's kindness: He deigned so generously to add sign to sign and to contend with the people's evil hearts, until with a strong hand He drew them out of their torpor of incredulity. Surely, if they neglected the first miracle, they were unworthy to have God set another proof of His power before them. It was, then, a wonderful exercise of longsuffering for Him still to persevere in countering their dullness.

With equal mercy He now overlooks our sluggishness of heart. For when we receive the testimonies by which He manifests His grace with far less reverence than we ought, He does not avenge our shameful ingratitude but rather adds new remedies to cure our unbelief.

Just as by the two former miracles God showed the power He intended to exercise by the hand of Moses, so in this third He taught them what His dealings with the Egyptians would be. Then, both from within and from without, Moses was confirmed before all the people. The conclusion, then, is that when God would lift up His hand against the Egyptians, they would be so far from having strength to resist that the very strongholds in which they proudly trusted would be found to be hostile and harmful to them.

We know how many and varied were the advantages they derived from the Nile. Their land, on one side, was made safe and invincible by its opposing barrier. Its many ports enriched their nation with convenient trade, both for importing and exporting merchandise. The fertility of their fields resulted from its floods. In short, Egypt attributed the main part of its prosperity to the Nile.

But now God warns not only that the Nile would not profit the Egyptians, but also that it was in His power to turn all its advantages into detriments. Indeed, He could make the very stream that used to fertilize their land by its irrigation cover and defile it with blood.

Regarding the words, "the voice of the sign" is used figuratively to mean a demonstration of God's power, by which the Israelites might be taught that Moses was sent to them by God as their deliverer. For although the rod turned into a serpent could not speak, it did indeed announce very loudly that what the Israelites considered altogether impossible would not be difficult for God.

Others interpret the particle את,⁵¹ as: “If they will not believe your voice, because of the sign”; but the former interpretation is more correct. The meaning of the expression, however, is clarified shortly afterward in this distinction — “If they will not believe also these two signs, neither listen to your voice.” This is as though God had said that His power cried out, or thundered, in His miracles to gain a hearing for His servant's teaching.

⁵¹ את the noun substantive translated a sign, and את the particle indicating an accusative case, are the same word in Hebrew, if points are not used. Hence Calvin has called the את here a particle, though avowedly commenting upon its purport as a noun. — W