From: Matthew 23:1-12
Vices of the Scribes and Pharisees
 Then said Jesus to the crowds and to His disciples,  "The scribes and the Pharisees sit on Moses' seat;  so practice and observe whatever they tell you, but not what they do; for they preach, but do not practice.  They bind heavy burdens, hard to bear, and lay them on men's shoulders; but they themselves will not move them with their finger.  They do all their deeds to be seen by men; for they make their phylacteries broad and their fringes long,  and they love the place of honor at feasts and the best seats in the synagogues,  and salutations in the market places, and being called rabbi by men.  But you are not to be called rabbi, for you have one teacher, and you are all brethren.  And call no man your father on earth, for you have one Father, who is in Heaven.  Neither be called masters, for you have one master, the Christ.  He who is greatest among you shall be your servant;  whoever exalts himself will be humbled, and whoever humbles himself will be exalted."
1-39. Throughout this chapter Jesus severely criticizes the scribes and Pharisees and demonstrates the sorrow and compassion He feels towards the ordinary mass of the people, who have been ill-used, "harassed and helpless, like sheep without a shepherd" (Matthew 9:36). His address may be divided into three parts: in the first (verses 1-12) He identifies their principal vices and corrupt practices; in the second (verses 13-36) He confronts them and speaks His famous "woes", which in effect are the reverse of the Beatitudes He preached in Chapter 5: no one can enter the Kingdom of Heaven--no one can escape condemnation to the flames--unless he changes his attitude and behavior; in the third part (verses 37-39) He weeps over Jerusalem, so grieved is He by the evils into which the blind pride and hardheartedness of the scribes and Pharisees have misled the people.
2-3. Moses passed on to the people the Law received from God. The scribes, who for the most part sided with the Pharisees, had the function of educating the people in the Law of Moses; that is why they were said to "sit on Moses' seat". Our Lord recognized that the scribes and Pharisees did have authority to teach the Law; but He warns the people and His disciples to be sure to distinguish the Law as read out and taught in the synagogues from the practical interpretations of the Law to be seen in their leaders' lifestyles. Some years later, St. Paul--a Pharisee like his father before him--faced his former colleagues with exactly the same kind of accusations as Jesus makes here: "You then who teach others, will you not teach yourself? While you preach against stealing, do you steal? You who say that one must not commit adultery, do you commit adultery? You who abhor idols, do you rob temples? You who boast in the law, do you dishonor God by breaking the law? For, as it is written, `The name of God is blasphemed among the Gentiles because of you'" (Romans 2:21-24).
5. "Phylacteries": belts or bands carrying quotations from sacred Scripture which the Jews used to wear fastened to their arms or foreheads. To mark themselves out as more religiously observant than others, the Pharisees used to wear broader phylacteries. The fringes were light-blue stripes on the hems of cloaks; the Pharisees ostentatiously wore broader fringes.
8-10. Jesus comes to teach the truth; in fact, He is the Truth (John 14:6). As a teacher, therefore, He is absolutely unique and unparalleled. "The whole of Christ's life was a continual teaching: His silences, His miracles, His gestures, His prayer, His love for people, His special affection for the little and the poor, His acceptance of the total sacrifice on the cross for the redemption of the world, and His resurrection are the actualization of His word and the fulfillment of revelation. Hence for Christians the crucifix is one of the most sublime and popular images of Christ the Teacher.
"These considerations are in line with the great traditions of the Church and they all strengthen our fervor with regard to Christ, the Teacher who reveals God to man and man to himself, the Teacher who saves, sanctifies and guides, who lives, who speaks, rouses, moves, redresses, judges, forgives, and goes with us day by day on the path of history, the Teacher who comes and will come in glory" (John Paul II, "Catechesi Tradendae", 9).
11. The Pharisees were greedy for honor and recognition: our Lord insists that every form of authority, particularly in the context of religion, should be exercised as a form of service to others; it must not be used to indulge personal vanity or greed. "He who is the greatest among you shall be your servant".
12. A spirit of pride and ambition is incompatible with being a disciple of Christ. Here our Lord stresses the need for true humility, for anyone who is to follow Him. The verbs "will be humbled", "will be exalted" have "God" as their active agent. Along the same lines, St. James preaches that "God opposes the proud, but gives grace to the humble" (James 4:6). And in the "Magnificat", the Blessed Virgin explains that the Lord "has put down the mighty from their thrones, and exalted those of low degree [the humble]" (Luke 1:52).
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.