John Calvin on Exodus 7:6-7

6. And Moses and Aaron did. It is not for the sake of boasting that Moses reports his own obedience; but after having ingenuously confessed his hesitation, he now relates that he and his brother were in better courage for the performance of their office. In the meantime he shows that he, as well as his brother, was God’s minister, and that he brought no industry, nor talent, nor counsel, nor dexterity himself, but simply obeyed God. Still from their example we must learn, that as we may not set about anything except what God prescribes, so we ought obediently and without objection to pursue whatever He commands. What follows as to their age is meant in amplification; since it was no common case, considering the natural coldness and heaviness of old age, that two octogenarians should have actively engaged in so difficult a charge. For I do not assent to the opinion of those who think that their dignity was enhanced by their age. I admit that age is venerable; but Moses had far different views, namely, that, excluding all human means, he might celebrate God’s glory, who performed so mighty a work by men who were failing and decrepit with age. For although their vigor was as yet unabated, their old age might have made them timid, and might have also affected the people with anxiety, when they beheld their leaders to be not only of advanced age, but even naturally not far from the grave.

Exodus 7:8-13

8. And the Lord spake unto Moses and unto Aaron, saying,

8. Et dixit Jehova ad Mosen et Aharon, dicendo.

9. When Pharaoh shall speak unto you, saying, Shew a miracle for you: then thou shalt say unto Aaron, Take thy rod, and cast it before Pharaoh, and it shall become a serpent.

9. Si loquutus fuerit ad vos Pharao, dicendo, Statuite vobis prodigium: tunc dices ad Aharon, Tolle virgam tuam, et projice coram Pharaone, et fiet in serpentem.

10. And Moses and Aaron went in unto Pharaoh, and they did so as the Lord had commanded: and Aaron cast down his rod before Pharaoh, and before his servants, and it became a serpent.

10. Venit ergo Moses et Aharon ad Pharaonem, et ita fecerunt ut praeceperat Iehova. Et projecit Aharon virgam suam coram Pharaone et coram servis ejus, et fuit in serpentem.

11. Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments.

11. Tunc vocavit etiam Pharao sapientes et incantatores, et fecerunt etiam ipsi magi Aegyptiorum hoc modo suis incantationibus.

12. For they cast down every man his rod, and they became serpents: but Aaron’s rod swallowed up their rods.

12. Projecerunt enim singuli virgas suas, quae fuerunt in dracones. Devoravit tamen virga Aharon virgas illorum.

13. And he hardened Pharaoh’s heart, that he hearkened not unto them; as the Lord had said.

13. Et obduravit cor Pharaonis, neque audivit illos, sicuti loquutus erat Jehova.