Dora Bas Rivka Silver O'H
No, Really... I Just Couldn't
G-d told Moshe to gather the elders of the people and tell them that G-d had sent him to take them out of Egypt to the Holy Land; G-d gave Moshe the "password" that Yoseif had communicated on his deathbed. (Compare 3:16 here with Genesis 50:24-25.) Moshe and the elders were to approach Pharaoh and ask for time off to make a three-day trip to worship G-d in the wilderness outside of Egypt. Of course, Pharaoh would not approve the request, at which point G-d would show him Who's Boss. G-d also assured Moshe that the people would not leave Egypt destitute; they would acquire the resources to build their own nation.
Next, Moshe objected that the Jews simply would not believe that G-d had sent him. G-d gave him three signs to prove his credentials. First, He enabled Moshe to toss down his staff, which would then turn into a snake. Second, Moshe could insert his hand into his cloak, only to remove it leprous. He could then return it to health. (Leprosy is the traditional punishment for slander; this sign was chosen because Moshe had spoken poorly of the Jewish people when he said they wouldn't believe G-d had sent him.) Finally, Moshe could scoop up fresh water from the river, which would turn to blood when he spilled it out. Those would be sufficient to satisfy even the most die-hard of cynics, G-d told Moshe.
Moshe's final objection was that he simply wasn't eloquent. No one would follow a leader with a speech impediment, he argued. G-d replied that He created the power of speech to begin with, so there was no reason for Moshe to worry about it. When Moshe continued to push this particular point, G-d said, "Enough! Your brother Aharon can serve as your spokesman. Now go already! And don't forget your staff - you're going to need that!"