Whereas the sign of Immanuel was for Ahaz primarily, the sign of Maher-shalal-hash-baz was for all the people of Judah. The preceding prophecies to Ahaz (7:10-25) are generally negative, but the following prophecies to the Judahites (8:1-10) are more positive.
Robert Chisholm, Jr., believed Maher-shalal-hash-baz was the immediate fulfillment of the Immanuel prophecy of 7:14.
"The juxtaposition of the birth report narrative (8:1-8) with the birth announcement narrative (7:14-25) suggests a close relationship between the prophecy and the birth. The pattern of events (initial deliverance followed by punitive judgment) associated with the growth pattern of the child is the same in both chapters. Also, Immanuel is addressed in the conclusion of the prophecy in chapter 9 (cf. 8:8) as if He were already present on the scene. This address makes excellent sense if one understands the introduction of the same message (8:1-3) as describing his birth.
"The differing names present a problem (which, by the way, one also faces in Matthew's application of the Immanuel prophecy to the birth of Jesus). Perhaps Immanuel, understood as a symbolic name, focuses on God's involvement in Judah's history, whereas Maher-Shalal-Hash-Baz, the child's actual name, alludes to the specific purpose or effect of His involvement. (In the same way, when applied to Jesus, Immanuel' attests to God's personal intervention in history through the Incarnation, whereas the Lord's actual name, Jesus, indicates the specific purpose or effect of that intervention.)"107
8:1 Yahweh instructed Isaiah to take a large flat surface (Heb. gillayon) appropriate for posting as a placard. He was to write clearly on it Maher-shalal-hash-baz("speeding to the plunder, hurrying to the spoil").
"Soldiers would shout these words to their comrades as they defeated and plundered their foes."108
This public notice had a double purpose: to announce a coming attack on Syria and Israel and to announce the birth of Isaiah's son.
"Isaiah was to make his message as public and eye-catching as possible."109
8:2 God selected two men whom he wanted to witness this document. When the predicted events happened, they could faithfully testify that Isaiah had predicted them. One of the witnesses was Uriah. He was probably the high priest who built an altar like the one in Damascus that Ahaz had seen and set it up in place of the brazen altar (cf. 2 Kings 16:10-16). The position that this Zechariah occupied is unknown, but he must have been a prominent public figure like Uriah (cf. 2 Chron. 26:5; 29:12-13).
8:3 Then Isaiah had sexual relations with his wife.110By naming her son Immanuel she made a prophetic statement: God would be with His people in the coming crisis. When she bore a son, Yahweh told Isaiah to name him Maher-shalal-hash-baz. The child's mother gave him one name and his father gave him the other.
8:4 Before the boy grew old enough to speak distinctly, Assyria (Tiglath-pileser III) would carry off the wealth of Damascus and Samaria (in 732 B.C.; cf. 7:15-16; 2 Kings 15:29). Thus Syria and Israel would not only fail in their attempt to bring Judah under their power (cf. 7:6), but the king of Assyria would bring them under his power. This second promise is almost identical to the earlier one in 7:4-9. Perhaps God intended it to be a second witness to the truthfulness of His word.
