Isaiah 21:6

The prophecy is continued with the conjunction "for" (ci). The tacit link in the train of thought is this: they act thus in Babylon, because the destruction of Babylon is determined. The form in which this thought is embodied is the following: the prophet receives instruction in the vision to set a metzappeh upon the watch-tower, who was to look out and see what more took place. "For thus said the Lord to me, Go, set a spy; what he seeth, let him declare." In other cases it is the prophet himself who stands upon the watch-tower (Isa 21:11; Hab 2:1-2); but here in the vision a distinction is made between the prophet and the person whom he stations upon the watch-tower (specula). The prophet divides himself, as it were, into two persons (compare Isa 18:4 for the introduction; and for the expression "go," Isa 20:2). He now sees through the medium of a spy, just as Zechariah sees by means of the angel speaking in him; with this difference, however, that here the spy is the instrument employed by the prophet, whereas there the prophet is the instrument employed by the angel.

In this chapter we have a prophecy of sad times coming, and heavy burdens, I. Upon Babylon, here called "the desert of the sea," that it should be destroyed by the Medes and Persians with a terrible destruction, which yet God's people should have advantage by (Isa 21:1-10). II. Upon Dumah, or Idumea (Isa 21:11, Isa 21:12). III. Upon Arabia, or Kedar, the desolation of which country was very near (Isa 21:13-17). These and other nations which the princes and people of Israel had so much to do with the prophets of Israel could not but have something to say to. Foreign affairs must be taken notice of as well as domestic ones, and news from abroad enquired after as well as news at home.