Luke 3:4-6 NIV

4 As is written in the book of the words of Isaiah the prophet: "A voice of one calling in the desert, 'Prepare the way for the Lord, make straight paths for him.
5 Every valley shall be filled in, every mountain and hill made low. The crooked roads shall become straight, the rough ways smooth.
6 And all mankind will see God's salvation.' "a1

References for Luke 3:6