Shew a miracle for you. — Pharaoh had perhaps heard of the miracles wrought by Aaron before the people of Israel (Exodus 4:30), and was curious to be an eye-witness of one, as was Herod Antipas (Luke 23:8). Or he may have thought that if Moses and Aaron “shewed a miracle,” his own magicians would be able to show greater ones, and he would then dismiss the brothers as charlatans and impostors. He certainly did hot intend to be influenced by any miracle which they might show, or to accept it as evidence that their message to him was a command from God.
Thy rod. — The rod is now called Aaron’s, because Moses had entrusted him with it. (Comp. Exodus 7:19, and Exodus 8:5; Exodus 8:16-17.)
A serpent. — Or, a snake. The word is not the same as that used in Exodus 4:3, but appears to be a synonym.