(Isa. 8:18; refer in this text to 2 Ne. 18:1–4)
The Prophet reminds the people of the fact that both he and his children were signs and wonders given them by the Lord as testimonies of his predictions. The names of two of his sons are recorded: Shear-jashub (Isa. 7:3) and Maher-shalal-hash-baz (Isa. 8:3). Whether Immanuel, mentioned in Isaiah 7:14 and 8:8, was the second son of Isaiah is a debated question… . It seems to me that the context of Isaiah 7:14 compels us to regard the virgin, the “alma” of that text as a young woman living at the time of King Ahaz and the prophet; for, how could her motherhood otherwise have been a sign to the skeptic king, for whom it was intended? … We notice that Isaiah, before the birth of Maher-shalal-hash-baz, undoubtedly following divine instructions, summoned two competent witnesses to accompany him to the mother of the expected child, to ascertain to their own satisfaction and to disarm public criticism, that she, the “prophetess,” was the legal wife of the Prophet. And, is it not probable that she was given that title, because she was the mother of the prophetic child Immanuel,—the type of the Messiah?
(George Reynolds and Janne M. Sjodahl, Commentary on the Book of Mormon, 7 vols., ed. Philip C. Reynolds [Salt Lake City: Deseret Book Co., 1955–1961], 1:346.)