Isaiah 7:13-14 NIV
Then Isaiah said,
Hear now, you house of David! 
Is it not enough to try the patience of humans?
Will you try the patience of my God also? 
Therefore the Lord himself will give you a sign: 
The virgin will conceive and give birth to a son, and will call him Immanuel.

Luke 2:4-12 NIV
So Joseph also went up from the town of Nazareth in Galilee to Judea, to Bethlehem the town of David, because he belonged to the house and line of David. He went there to register with Mary, who was pledged to be married to him and was expecting a child. While they were there, the time came for the baby to be born, and she gave birth to her firstborn, a son. She wrapped him in cloths and placed him in a manger, because there was no guest room available for them.

And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. But the angel said to them, Do not be afraid. I bring you good news that will cause great joy for all the people. Today in the town of David a Saviour has been born to you; he is the Messiah, the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.