1 A prophecy against Egypt: See, the Lord rides on a swift cloud and is coming to Egypt. The idols of Egypt tremble before him, and the hearts of the Egyptians melt with fear.
2 “I will stir up Egyptian against Egyptian—brother will fight against brother, neighbor against neighbor, city against city, kingdom against kingdom.
3 The Egyptians will lose heart, and I will bring their plans to nothing; they will consult the idols and the spirits of the dead, the mediums and the spiritists.
4 I will hand the Egyptians over to the power of a cruel master, and a fierce king will rule over them,” declares the Lord, the Lord Almighty.
From chapter sixteen we skip over chapter seventeen, A Prophecy Against Damascus, and chapter eighteen, A Prophecy Against Cush, and move on to chapter nineteen because it is here the heart is mentioned four (!) times.
Concerning the prophecy against Egypt one has to believe they remembered from hand me down histories how the God of Israel used ten plagues to humiliate ten Egyptian gods and goddesses during the time of Moses. Check out the link for more detail on how the one true God took care to do so one by one. Thus it is no wonder to me that the hearts of the Egyptians melt with fear upon hearing the prophecy.
It is the same in verse three, they will lose heart, their idols will not help nor the spirits of the dead nor the mediums and spiritists. None of them helped when God was making a way for His people to leave Egypt, nor will they help now.
It is important to worship the one true God and not idols nor spirits nor those who call upon the dead. It is also important to have a book that provides what we need to actually know the God we worship. Just as He can bring destruction, He can also show incredible love
16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. 17 For God did not send his Son into the world to condemn the world, but to save the world through him. 18 Whoever believes in him is not condemned, but whoever does not believe stands condemned already because they have not believed in the name of God’s one and only Son. 19 This is the verdict: Light has come into the world, but people loved darkness instead of light because their deeds were evil. (John 3)
Choose the light not the darkness.