Exodus 4:5

5.That they may believe. This spectacle, then, was not shewn to Moses once only, but the power was imparted to him also of frequently repeating the miracle; both to acquire credit from the Israelites, and to repress the audacity of Pharaoh. For although the sentence is incomplete, there is no ambiguity in the sense, viz., that Moses is armed with power from heaven to make his vocation sure, and that none may doubt him to be a Prophet divinely commissioned. It would be tedious here to dilate expressly on the use of miracles, suffice it briefly to lay down, that they sometimes serve as preparatives to faith, sometimes for its confirmation. We see an example of both in the metamorphosis of the rod, by which Moses was the more animated and encouraged to gather strength, although he already believed God’s promise; but the Israelites, who were both incredulous and unteachable, were prepared and compelled to believe. Besides, the miracle opened a door of faith with the Israelites, that, being persuaded of his prophetical office, they might submit to be taught; whilst he was himself led on to greater assurance and perseverance. For although the Almighty begins further back, and refers to the adoption of the patriarchs, and this was calculated to lay the foundation of their hope of redemption, it still does not follow that they were prepared to receive Moses, until the authority of his ministry had been established. Wherefore, I have said, that their faith was commenced by the miracle.