Chapter 18 Ambassadors Come From Cush and Egypt.
Prior to his burden in respect of Egypt (Isaiah 19:1) Isaiah's thought now turn towards that land. This was the result of Cushite ambassadors arriving in Jerusalem with the usual purpose, to entangle God's people in their plots and schemes. The Cushites (Nubians) then ruled Egypt. Whether this was a preliminary enquiry, which was not followed up with action, or a genuine attempt to stir up rebellion with the intention of giving full support depends on the date of the visit. If the former it was sufficient to persuade a number of allies to take on the might of Assyria. If the latter it proved finally ineffective. But it was because the Cushites sought to have contact with God's people that the burden came on Isaiah, as it had in different ways with Babylon, Philistia, Moab and Syria. Once nations sought to influence God's people they came under the eye of God, and their attempts to lure God's people into worldly alliance were his constant burden.
Throughout the whole of these Chapter s 13-23 we see what is ever true for God's people, that there will always be those who seek to wean them away from God by any means they can. The world at that time was a hotbed of intrigue, and there were always those who would seek to draw God's people into it. But Isaiah's constant message was that Israel must not look to them, but must trust in God.