Matthew 3:1-6: "In those days John the Baptist came preaching in the wilderness of Judea, 'Repent, for the kingdom of heaven is at hand.' For this is he who was spoken of by the prophet Isaiah when he said, 'The voice of one crying in the wilderness: "Prepare the way of the Lord; make his paths straight."' Now John wore a garment of camel's hair and a leather belt around his waist, and his food was locusts and wild honey. Then Jerusalem and all Judea and all the region about the Jordan were going out to him, and they were baptized by him in the river Jordan, confessing their sins."
Isaiah 40:3: "A voice cries: 'In the wilderness prepare the way of the LORD; make straight in the desert a highway for our God.'"
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The text is public domain:
On Jordan's bank the Baptist's cry
Announces that the Lord is nigh;
Awake and hearken, for he brings
Glad tidings of the King of kings!
Then cleansed be ev'ry life from sin;
Make straight the way for God within,
And let us all our hearts prepare
For Christ to come and enter there.
We hail Thee as our Savior, Lord,
Our refuge and our great reward;
Without Thy grace we waste away
Like flow'rs that wither and decay.
Lay on the sick Thy healing hand
And make the fallen strong to stand;
Show us the glory of Thy face
Till beauty springs in ev'ry place.
All praise, eternal Son, to Thee
Whose advent sets Thy people free,
Whom with the Father we adore
And Holy Spirit evermore.
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The first verse is clearly from the Matthew text. The first two lines of the second verse ("Then cleansed be ev'ry life from sin; / Make straight the way for God within,") is an extension of either the Matthew text or the Isaiah text that it quotes, specifically: "make straight in the desert a highway for our God."
There don't seem to be any other specific Biblical references in the rest of the text. However, where the Lutheran Service Book has "Show us the glory of Thy face," Lutheran Worship has "Oh, let your face upon us shine," echoing the Aaronic blessing: "The LORD bless you and keep you; the LORD make his face to shine upon you and be gracious to you; the LORD lift up his countenance upon you and give you peace" (Numbers 6:24-26)
