Chapter 4 is a continuation of Moshe's encounter with G-d at the burning bush. In Chapter 3 Moshe voiced 2 objections in verse 11 he asked "Who am I ..." then in verse 13 he asked, "What is His name..." In chapter 4 he will voice more objections.
Sh'mot 4:1 Then Moshe answered and said, "What if they will not believe me, or listen to what I say? For they may say, 'The L-RD has not appeared to you.'"
Here we see Moshe's 3rd objection.
Sh'mot 4:2-9 And the L-RD said to him, "What is that in your hand?" And he said, "A staff." Then He said, "Throw it on the ground." So he threw it on the ground, and it became a serpent; and Moshe fled from it. But the L-RD said to Moshe, "Stretch out your hand and grasp it by its tail"-- so he stretched out his hand and caught it, and it became a staff in his hand-- "that they may believe that the L-RD, the G-d of their fathers, the G-d of Avraham, the G-d of Yitz'chak, and the G-d of Ya'akov, has appeared to you." And the L-RD furthermore said to him, "Now put your hand into your bosom." So he put his hand into his bosom, and when he took it out, look, his hand was leprous like snow. Then He said, "Put your hand into your bosom again." So he put his hand into his bosom again; and when he took it out of his bosom, look, it was restored like the rest of his flesh. And it shall come about that if they will not believe you or heed the witness of the first sign, they may believe the witness of the last sign. But it shall be that if they will not believe even these two signs or heed what you say, then you shall take some water from the Nile and pour it on the dry ground; and the water which you take from the Nile will become blood on the dry ground."
The corresponding letter to this chapter is Dalet-door; way; symbol of dimensions and concern.
The important thing to remember here are the signs that the G-d of Avraham, Yitz'chak, and Ya'akov use to tell His people that He was the real deal.
A snake, a leper and water turned into blood. Lets look at these three signs in more detail.
During the Exodus, a bronze snake would be hung on a pole and those that looked at it would be healed. Much later the Messiah too would be hung on a pole to heal us spiritually from our sin, which leads to death. Why would G-d use the symbol of the snake? Because the snake was cursed by G-d. (See B'resheet (Genesis) chapter 3.) The Messiah also would be considered cursed as He hung on the execution stake.
Galatians 3:12-14 However, the Law (instruction) is not of faith; on the contrary, "He who practices them shall live by them." Messiah redeemed us from the curse of the Law (because of our sin), having become a curse for us-- for it is written, "Cursed is everyone who hangs on a tree"-- in order that in Messiah Yeshua the blessing of Avraham might come to the Gentiles, so that we might receive the promise of the Spirit through faith. NAS
How do we know who the Messiah is later?
The serpent would also point to the Real deal and the way we should follow to eternal healing.
B'midbar (Numbers) 21:8-9 Then the L-RD said to Moshe, "Make a fiery serpent, and set it on a standard; and it shall come about, that everyone who is bitten, when he looks at it, he shall live." And Moshe made a bronze serpent and set it on the standard; and it came about, that if a serpent bit any man, when he looked to the bronze serpent, he lived. NAS
Also notice it states "fiery" and "bronze". Again just like the real deal.
The Son of G-d, (remember not like you or I having a son) one who has eyes like a flame of fire, and His feet are like burnished bronze, NAS
Revelation 1:13-17 and in the middle of the lampstands one like a son of man, clothed in a robe reaching to the feet, and girded across His breast with a golden girdle. And His head and His hair were white like white wool, like snow; and His eyes were like a flame of fire; and His feet were like burnished bronze, when it has been caused to glow in a furnace, and His voice was like the sound of many waters. And in His right hand He held seven stars; and out of His mouth came a sharp two-edged sword; and His face was like the sun shining in its strength.
Leprosy is symbolic of sin. Moshe is a type of Yeshua. HaShem placed leprosy on Moshe for a time and then healed him of it. In the same way HaShem placed our sins on Yeshua when He died in our place. Because He was willing to do this, our sins can be forgiven too. All we need to do is accept Him as our Messiah. Trusting His death alone paid for our sins.
His concern for and healing of a leper would also point us to the Real Deal.
Mattityahu (Matthew) 8:1-4 Large crowds followed Yeshua as he came down the hillside. Look! A leper is approaching. He kneels before Him, worshiping. "Sir," the leper pleads, "if you want to, you can heal me." Yeshua touches the man. "I want to," He says. "Be healed." And instantly the leprosy disappears. Then Yeshua says to him, "Don't stop to talk to anyone; go right over to the Cohen to be examined; and take with you the offering required by Moshe' law for lepers who are healed-a PUBLIC TESTIMONY of your cure."
Yeshua would turn water into wine. Wine symbolic of the blood covenant.
Yochanan (John) 2:6-11 Now there were six stone waterpots set there for the Jewish custom of purification, containing twenty or thirty gallons each. Yeshua said to them, "Fill the waterpots with water." And they filled them up to the brim. And He said to them, "Draw some out now, and take it to the headwaiter." And they took it to him. And when the headwaiter tasted the water which had become wine, and did not know where it came from (but the servants who had drawn the water knew), the headwaiter called the bridegroom, and said to him, "Every man serves the good wine first, and when men have drunk freely, then that which is poorer; you have kept the good wine until now." NAS
Mattityahu (Matthew) 26:27-28 And when He had taken a cup and given thanks, He gave it to them, saying, "Drink from it, all of you; for this is My blood of the covenant, which is poured out for many for forgiveness of sins. NAS
This generation is privileged to have many signs. What will be your excuse for not believing?
Who is the G-d of Avraham, Yitz'chak, and Ya'akov?
Who was, and is, and is to come? Surely you know!
Every page of the Tanakh points to His coming.