Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[284] But when the king derided Moses; he made him in earnest see the signs that were done at Mount Sinai. Yet was the king very angry with him and called him an ill man, who had formerly run away from his Egyptian slavery, and came now back with deceitful tricks, and wonders, and magical arts, to astonish him. And when he had said this, he commanded the priests to let him see the same wonderful sights; as knowing that the Egyptians were skillful in this kind of learning, and that he was not the only person who knew them, and pretended them to be divine; as also he told him, that when he brought such wonderful sights before him, he would only be believed by the unlearned. Now when the priests threw down their rods, they became serpents. But Moses was not daunted at it; and said, "O king, I do not myself despise the wisdom of the Egyptians, but I say that what I do is so much superior to what these do by magic arts and tricks, as Divine power exceeds the power of man: but I will demonstrate that what I do is not done by craft, or counterfeiting what is not really true, but that they appear by the providence and power of God." And when he had said this, he cast his rod down upon the ground, and commanded it to turn itself into a serpent. It obeyed him, and went all round, and devoured the rods of the Egyptians, which seemed to be dragons, until it had consumed them all. It then returned to its own form, and Moses took it into his hand again.