From: Luke 7:24-30
The Mission of John the Baptist (Continuation)
 When the messengers of John had gone, He (Jesus) began to speak to the crowds concerning John: "What did you go out into the wilderness to behold? A reed shaken by the wind?  What then did you go out to see? A man clothed in soft raiment? Behold, those who are gorgeously appareled and live in luxury are in kings' courts.  What then did you go out to see? A prophet? Yes, I tell you, and more than a prophet.  This is he of whom it is written, `Behold, I send My messenger before Thy face, who shall prepare Thy way before Thee.'  I tell you, among those born of women none is greater than John; yet he who is least in the Kingdom of God is greater than he."  (When they heard this all the people and the tax collectors justified God, having been baptized with the baptism of John;  but the Pharisees and the lawyers rejected the purpose of God for themselves, not having been baptized by him.)
28. St. John the Baptist is the greatest of the prophets of the Old Testament because he was nearest to Christ and received the unique mission of actually pointing out the Messiah. Still, he belongs to the time of the promise (the Old Testament), when the work of redemption lay in the future. Once Christ did that work (the New Testament), those who faithfully accept God's gift of grace are incomparably greater than the righteous of the Old Covenant who were given, not this grace, but only the promise of it. Once the work of redemption was accomplished God's grace also reached the righteous of the Old Testament, who were waiting for Christ to open Heaven and let them, too, enter.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.