19 And I am sure that the king of Egypt will not let you go, no, not by a mighty hand.
Exodus 3:19 Cross References - Webster
Exodus 5:2
2 And Pharaoh said, Who is the LORD, that I should obey his voice to let Israel go? I know not the LORD, neither will I let Israel go.
Exodus 6:1
1 Then the LORD said to Moses, Now shalt thou see what I will do to Pharaoh; for with a strong hand shall he let them go, and with a strong hand shall he drive them from his land.
Exodus 7:1-14
1 And the LORD said to Moses, See, I have made thee a god to Pharaoh: and Aaron thy brother shall be thy prophet.
2 Thou shalt speak all that I command thee: and Aaron thy brother shall speak to Pharaoh, that he send the children of Israel out of his land.
3 And I will harden Pharaoh's heart, and multiply my signs and my wonders in the land of Egypt.
4 But Pharaoh shall not hearken to you, that I may lay my hand upon Egypt, and bring forth my armies, my people the children of Israel, out of the land of Egypt, by great judgments.
5 And the Egyptians shall know that I am the LORD, when I stretch forth my hand upon Egypt, and bring out the children of Israel from among them.
6 And Moses and Aaron did as the LORD commanded them, so did they.
7 And Moses was eighty years old, and Aaron eighty and three years old, when they spoke to Pharaoh.
8 And the LORD spoke to Moses, and to Aaron, saying,
9 When Pharaoh shall speak to you, saying, Show a miracle for you: then thou shalt say to Aaron, Take thy rod, and cast it before Pharaoh, and it shall become a serpent.
10 And Moses and Aaron went in to Pharaoh, and they did so as the LORD had commanded: And Aaron cast down his rod before Pharaoh, and before his servants, and it became a serpent.
11 Then Pharaoh also called the wise-men, and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments.
12 For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods.
13 And he hardened Pharaoh's heart that he hearkened not to them; as the LORD had said.
14 And the LORD said to Moses, Pharaoh's heart is hardened; he refuseth to let the people go.