Isaiah 7:3

Go forth now. Although Ahaz himself was a wicked king, the Lord had no intention of allowing the dynasty of David to become extinct (see Gen. 49:10; 2 Sam. 7:12, 13). Therefore Isaiah was sent to the king to inform him of the Lord’s purpose to preserve Judah and to defeat its invaders.

Shear-jashub. Literally, “[a] remnant [shall] return.” Isaiah and his sons were ordained of God as signs to the people (ch. 8:18). The same was true of Isaiah’s contemporary, Hosea, whose children also bore significant names (Hosea 1:4-9). Isaiah constantly kept this message of the return of the remnant before the people (chs. 4:2, 3; 10:21; etc.).

The upper pool. The water supply of the city was always a matter of importance at a time of siege. The “upper pool” has been identified with the upper pool of Gihon, known as St. Mary’s Well or the Virgin’s Fount (see Jerusalem in Israelite Times). It was situated in the Kidron Valley on the east side of Ophel and south of the Temple area. It was from Gihon that Hezekiah later made his famous aqueduct, the Siloam tunnel (2 Kings 20:20; 2 Chron. 32:30), which brought the water to the Siloam pool within the city. At the time of Ahaz this source of water would be outside the city at a time of siege, and undoubtedly some steps were then contemplated as to how the water might be brought into the city and denied to an enemy without.