The Messiah would be born of a virgin.
OT Prophecy NT Fulfillment
Isaiah 7:14a
[14] Therefore the LORD himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
Luke 1:34–35
[34] Then said Mary unto the angel, How shall this be, seeing I know not a man?
[35] And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
Tanakh – Neviim – Isaiah 7:14
[7:14] Therefore the Lord Himself shall give you a sign: behold, the young woman shall conceive, and bear a son, and shall call his name Immanuel.
Hebrew OT – Isaiah 7:14
[7:14] לָכֵן יִתֵּן אֲדֹנָי הוּא לָכֶם אוֹת
הִנֵּה הָעַלְמָה הָרָה וְיֹלֶדֶת בֵּן
וְקָרָאת שְׁמוֹ עִמָּנוּ אֵל