TSK · Mark 1:3

The voice of one who calls out, "Prepare the way of Yahweh in the wilderness! Make a level highway in the desert for our God.

As it is written in the book of the words of Isaiah the prophet, "The voice of one crying in the wilderness, 'Make ready the way of the Lord. Make his paths straight.

This is John's testimony, when the Jews sent priests and Levites from Jerusalem to ask him, "Who are you?"