In more detail, it appears Mark has taken part of Exodus 23:20 of the Septuagint: (Brenton Ex 23:20: "behold, I send my angel before thy face") and combined it with part of Malachi 3:1 of the Septuagint: (Brenton Mal 3:1: "survey the way") to create in the Westcott-Hort Greek NT: . The significant differences are ("survey" -Brenton) is replaced with ("prepare" -NRSV) and a final ("your" -NRSV) has been added: "See, I am sending my messenger ahead of you, who will prepare your way" ( in the NRSV). The following quote of Isaiah 40:3 is specifically from the Septuagint, compare Brenton Isa 40:3: "The voice of one crying in the wilderness, Prepare ye the way of the Lord, make straight the paths of our God." to the Masoretic Text : "Hark! one calleth: 'Clear ye in the wilderness the way of the LORD, make plain in the desert a highway for our God." or the NRSV : "A voice cries out: ‘In the wilderness prepare the way of the Lord, make straight in the desert a highway for our God." or the new JPS Tanakh (1985) 40:3: "A voice rings out: Clear in the desert A road for the Lord! Level in the wilderness A highway for our God!"