God then spoke to him—comforting him and teaching him that He is able to do all things, He who only says to a thing, “Be!” and it is—saying, “And what is that in your right hand, O Moses?” That is: Is this not the very staff we have always known you to carry?
He answered, “It is my staff; I lean on it, and with it I beat down leaves for my sheep, and I have other uses for it as well.” In other words: Yes, it is indeed my staff, the one I know and recognize.
The Lord said, “Cast it down, O Moses.” So he cast it, and thereupon it became a writhing serpent. (Ta Ha 20:19–20) This was an astounding miracle and an unassailable proof that the One addressing him is the One who says to a thing, “Be!” and it is—the One who acts by His own volition.
According to the People of the Scripture, Moses had asked for a sign to prove his truthfulness before those in Egypt who would deny him. The Lord therefore said to him, “What is that in your hand?” He replied, “A staff.” The Lord said, “Throw it to the ground,” and when he threw it, it became a snake. Moses fled from it, but the Lord commanded him to stretch out his hand and seize it by the tail. Once he had a firm grip on it, it returned in his hand to a staff once more.
God also says in another verse: “And cast down your staff. When he saw it quivering as though it were a jān-serpent, he turned in flight and did not look back.” That is, it had become a gigantic snake of awesome girth and clashing fangs, yet it moved with the speed of the jān—a type of serpent, small but extremely quick and restless. Here, huge size was combined with extreme agility. When Moses beheld it, he turned and ran—for such is human nature—without once glancing back. His Lord then called to him, “O Moses, come forward and fear not; you are of those who are secure.” When he returned, God Most High commanded him to grasp it: “Seize it and fear not; We shall restore it to its former state.” (Ta Ha 20:21)
It is said that Moses was so afraid of it that he tucked his hand into the sleeve of his tunic and then placed that hand into the very middle of its mouth. According to the People of the Scripture, he seized it by its tail. Once he held it firmly, it reverted to what it had been—a forked staff. Glory be to the All-Powerful, the Majestic, Lord of the two Easts and the two Wests.
Next the Most High commanded him to place his hand inside his garment and then draw it out; it emerged gleaming white as the moon, “without any harm”—meaning without leprosy or vitiligo. Hence His words: “Insert your hand into your garment; it will come out white, without blemish, and draw your arm to yourself to dispel your fear.” (al-Qasas 28:32) It has been said that the meaning is: whenever you feel afraid, place your hand upon your chest and your heart will be calmed. Though this instruction was specific to him, the blessings of faith in him make it beneficial to follow such prophetic practice.
In Sūrah al-Naml He says: “Insert your hand into your garment; it will come out white, without blemish—among nine signs to Pharaoh and his people, for they are a defiantly disobedient folk.” (27:12) Thus these two signs—the staff and the hand—are the very two proofs referred to in His words: “So those two….”