EXODUS: The Lord God Sends the Second Plague in Egypt; "Thus says the Lord: 'Let My people go, that they may serve Me. But if you refuse to let them go, behold, I will smite all your territory with frogs.'"

He sent Moses His servant, and Aaron whom He had chosen. They performed His signs among them, and wonders in the land of Ham. (Psalm 105:26-27) 

Their land abounded with frogs, even in the chambers of their kings. (Psalm 105:30)

And the Lord spoke to Moses, “Go to Pharaoh and say to him, ‘Thus says the Lord: “Let My people go, that they may serve Me. But if you refuse to let them go, behold, I will smite all your territory with frogs. So the river shall bring forth frogs abundantly, which shall go up and come into your house, into your bedroom, on your bed, into the houses of your servants, on your people, into your ovens, and into your kneading bowls. And the frogs shall come up on you, on your people, and on all your servants.”’” (Exodus 8:1-4) 

Then the Lord spoke to Moses, “Say to Aaron, ‘Stretch out your hand with your rod over the streams, over the rivers, and over the ponds, and cause frogs to come up on the land of Egypt.’” So Aaron stretched out his hand over the waters of Egypt, and the frogs came up and covered the land of Egypt. (Exodus 8:5-6) Frogs represented several of Egypt's gods. "The frog goddess Heqet was often shown as a frog-headed woman or as a frog. Because the Egyptians saw that there were many frogs, all appearing from the Nile, they associated the frog with fertility and resurrection, and so Heqet was a goddess of childbirth." (read "Heqet, Frog Headed Goddess...")

In the first plague, the Lord God turned all of the Egyptian waters in the rivers into blood.  The Nile River was their culture's "lifeblood", so the Lord God attacked it first. Now secondly, the Lord God attacked them with the symbol of one of their gods, the frog. The idols of Egypt will totter at His presence,... (Isaiah 19:1) But Pharaoh, as before called in his magicians to see if they could perform a similar miracle. And the magicians did so with their enchantments, and brought up frogs on the land of Egypt. Then Pharaoh called for Moses and Aaron, and said, “Entreat the Lord that He may take away the frogs from me and from my people; and I will let the people go, that they may sacrifice to the Lord.” (Exodus 8:7-8) 

And Moses said to Pharaoh, “Accept the honor of saying when I shall intercede for you, for your servants, and for your people, to destroy the frogs from you and your houses, that they may remain in the river only.” So he said, “Tomorrow.” And he said, “Let it be according to your word, that you may know that there is no one like the Lord our God. And the frogs shall depart from you, from your houses, from your servants, and from your people. They shall remain in the river only.” (Exodus 8:9-11)

Pharaoh's magicians brought up frogs on the land of Egypt, but obviously they couldn't make them return to the river, so therefore, he called Moses and Aaron. He used the phrase “Entreat the Lord ", but not out of belief in Him or sincerity.  He just wanted the frogs removed, and if Moses and Aaron could make that happen, he'd say anything. The Lord God ...will both bring to light the hidden things of darkness and reveal the counsels of the hearts. (I Corinthians 4:5)

Then Moses and Aaron went out from Pharaoh. And Moses cried out to the Lord concerning the frogs which He had brought against Pharaoh. So the Lord did according to the word of Moses. And the frogs died out of the houses, out of the courtyards, and out of the fields. They gathered them together in heaps, and the land stank. But when Pharaoh saw that there was relief, he hardened his heart and did not heed them, as the Lord had said. (Exodus 8:12-15)

And the Lord God did indeed reveal the counsels of Pharaoh's heart, he hardened his heart.  All Pharaoh wanted was the relief, and once he received it, he went back to his evil ways. Often times we do the same thing, we do what we want, mess up miserably, call to God for help, out of His mercy He may help us, and then once we receive relief, we go back to doing the same things we used to do that got us in trouble in the first place. Draw near to God and He will draw near to you. Cleanse your hands, you sinners; and purify your hearts, you double-minded. (James 4:8) He who covers his sins will not prosper, but whoever confesses and forsakes them will have mercy. (Proverbs 28:13) 

All Pharaoh was doing was "heaping coals of fire on his head"; For judgment is without mercy to the one who has shown no mercy. (James 2:13) His total disregard and disrespect for the power, authority and mercy of God would cause the Lord God to send the third plague on Egypt...