What happened when God told Moses to throw his rod on the ground?
When Moses obeyed and cast his shepherd's rod on the ground, it became a serpent. Moses fled from before it, for the serpent was real and could be deadly. God then told him to take it by the tail, and it immediately reverted back to his shepherd's rod.
Les explains that when Moses cast the rod down, it became a real serpent, and Moses fled because Middle Eastern serpents can be deadly poisonous. The Lord then told Moses to put forth his hand and take it by the tail—something Les notes is not the safe way to handle a live snake—and Moses obeyed. Immediately it reverted back to his shepherd's rod. Les points out this is the beginning of what Paul claims in 1 Corinthians chapter 1, verse 22, that the Jews require a sign. All through Israel's history, God used signs and miracles as proof, beginning with Moses before Pharaoh and the children of Israel.
And the LORD said unto him, What is that in thine hand? And he said, A rod.
And he said, Cast it on the ground. And he cast it on the ground, and it became a serpent; and Moses fled from before it.