Exodus 4:4

Take it by the tail. — Those who venture to handle poisonous snakes, like the modern Egyptians and the inhabitants of the coast of Barbary, generally take hold of them by the neck, in which case they are unable to bite. To test the faith and courage of Moses, the command is given him to lay hold of this serpent “by the tail.”

He put forth his hand. — Faith triumphed over instinct. Moses had “fled from” the snake when first he saw it (Exodus 4:3). Now he is daring enough to stoop down, put his hand on the creature’s tail, and so lift it up.

It became a rod. — Its real nature returned to it. Once more it was, not a stiffened serpent, but an actual staff, or walking-stick.