'As It is Written' in the Bible

Now when the period of their purification ended, in accordance with the law of Moses, they took Him up to Jerusalem to present Him to the Lord, to do as it is written in the law of the Lord,

as it is written in the sermon-book of the prophet Isaiah: "Here is a voice of one shouting in the desert, 'Get the road ready for the Lord, make the paths straight for Him.