Thus far the prophecy is one that would be accepted with glee by Judah. To this point, the prophecy simply says that the kingdoms of Syria and Israel that are conspiring against Judah will be devastated. Should not Judah rejoice over the destruction of her enemies?
The prophecy will now turn to the subject of Judah. At the end of the verse, Isaiah states the obvious, that Judah will rejoice in the defeat of the kings of Syria and Israel. Even though he is not explicit in the phrase that it is the defeat in which the people rejoice, it is the clear referent, and easily understandable.
Literary analysis: That leaves us with the opening phrase that is given as a reason for the coming woes of Judah; they “refuse... the waters of Shiloah that go softly.” The image of the waters is critical, for it forms a paired set with the water symbolism in the next verse.
“The gentle waters of Shiloah were the major water source for ancient Jerusalem. Located at the Gihon spring in the Kidron Valley east fo the fortified city, they ebb and flow continually throughout the year. During Isaiah’s life, the waters were brought into a fortified area of the city when King Hezekiah, the son of Ahaz, built a tunnel through Mount Ophel, which still carries from eight to forty inches of running water. The cool, flowing spring supplied more than enough water for the city of Jerusalem.” (Ludlow, p. 145).
The waters of Shiloah become in this reference not simply a symbol for Jerusalem, but for the God who provides for and protects them. Isaiah uses the image of the refusal of the waters of Shiloah as a type of Judah’s refusal of the protection of the Lord. Ahaz refused the sign of the Lord’s protection in the prophecy in chapter 17. In this chapter, the people of Judah are said to follow the lead of their King in declining to trust in their Lord.