Luke 3:4

Ἡσαΐου τοῦ προφήτου. Isaiah 40:3.

[λέγοντος.] This word should be omitted with אBDL, &c.

φωνή. ‘A voice.’ The Hebrew original may be rendered “Hark, one crieth.” St Luke does not follow the other Synoptists in the identification of John with the promised Elias (Matthew 17:13; Mark 9:13).

βοῶντος ἐν τῇ ἐρήμῳ. Hence comes the common expression for hopeless warnings, vox clamantis in deserto. Probably, however, the “in the wilderness” should be attached to the words uttered by the voice, as is required by the parallelism of Hebrew poetry:

“Prepare ye in the wilderness a way for Jehovah,
Level in the desert a highway for our God.”

The wilderness is metaphorically the barren waste of the Jewish life in that day (Isaiah 35:1).

ὁδὸν κυρίου. Comp. Isaiah 35:8-10, “And a highway shall be there, and a way, and it shall be called the way of holiness: the unclean shall not pass over it … And the ransomed of the Lord shall return, and come to Zion.”