Matthew 21:3 - Albert Barnes' Notes on the Bible

The Lord hath need of them - This means no more than the “master” has need of them. The word “Lord” often means no more than “master” as opposed to servant, Matthew 10:24; Eph 6:5; 1 Peter 3:5-6. The word is sometimes used in the Bible as applied to God, or as a translation of the name Yahweh. Its common use is a mere title of respect given by an inferior to a superior, by a servant to a master, by a disciple to a teacher. As a title of “high respect” it was given to Christ, or the Messiah. The persons to whom these disciples were sent were probably acquainted with the miracles of Jesus and favorably disposed toward him He had attracted great notice in that region, particularly by raising Lazarus from the dead, and most of the people regarded him as the Messiah.