Isaiah 18:2
2 That sendeth ambassadors by the sea, even in vessels of bulrushes upon the waters, saying, Go, ye swift messengers, to a nation scattereda and peeled, to a people terrible from their beginning hitherto; a nation meted out and trodden down, whose land the rivers have spoiled!
That sendeth ambassadors
The local reference is evidently to an embassy from Egypt, resulting in the alliance denounced in Isaiah 30, 31, (Jeremiah 37:7).