Albert Barnes Commentary Matthew 11:10

"This is he, of whom it is written, Behold, I send my messenger before thy face, Who shall prepare thy way before thee." — Matthew 11:10 (ASV)

For this is he, etc. The passage of Scripture here quoted is found in Malachi 3:1. The substance of it is also contained in Isaiah 40:3.

Prepare thy way. That is, to prepare the people; to make them ready, by proper instructions, to receive the Messiah.