Isaiah 7:10-14 (KJV)
10 Moreover the Lord spake again unto Ahaz, saying,
11 Ask thee a sign of the Lord thy God; ask it either in the depth, or in the height above.
12 But Ahaz said, I will not ask, neither will I tempt the Lord.
13 And he said, Hear ye now, O house of David; Is it a small thing for you to weary men, but will ye weary my God also?
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.