isaiah 8:18 Behold, I and the children whom the LORD hath given me are for signs and for wonders in Israel from the LORD of hosts, which dwelleth in mount Zion. - Free Bible Online

      18. I and the children--Isaiah means "salvation of Jehovah"; His children's names, also (Isa 7:3, 14; 8:3), were "signs" suggestive of the coming and final deliverance.
      wonders--that is, symbols of the future (Isa 20:3; Zec 3:8). "Behold I . . . me" is quoted in Heb 2:13 to prove the manhood of the Messiah. This is the main and ultimate fulfilment of the prophecy; its temporary meaning is applied to Ahaz' time. Isaiah typically, in Isa 8:17, 18, personates Messiah, who is at once "Father" and "Son," Isaiah and Immanuel, "Child" and "Mighty God," and is therefore called here a "wonder," as in Isa 9:6, "Wonderful." Hence in Heb 2:13, believers are called His "children"; but in Isa 8:11, 12, His "brethren." On "the Lord hath given me," see Joh 6:37, 39; 10:29; 17:12.
      which dwelleth in . . . Zion--and will therefore protect Jerusalem.

JFB.