St. Chrysostom offers some fascinating insights about Jesus' confrontation with the Pharisees in Matthew 15:
Let us learn then what are the things that defile the man; let us learn, and let us flee them. For even in the church we see such a custom prevailing amongst the generality, and men giving diligence to come in clean garments, and to have their hands washed; but how to present a clean soul to God, they make no account.
And this I say, not forbidding them to wash hands or mouth; but willing men so to wash is meet, not with water only, but instead of water, with all virtues. For the filth of the mouth is evil speaking, blasphemy, reviling, angry words... If then thou art conscious to thyself of uttering none of them, neither of being defiled with this filth, draw near with confidence.
...For tell me, hadst thou dung on thy hands, and mire, wouldest thou indeed venture to pray? By no means. And yet this were no hurt; but that is ruin. How then art thou reverential in the different things, but in the forbidden remiss?
What then? should we not pray? saith one.
We should indeed, but not while defiled, and having upon us mire of that sort. 'What then, if I have been overtaken?' saith one. Cleanse thyself. 'How, and in what way?' Weep, groan, give alms, apologize to him that is affronted, reconcile him to thyself hereby, wipe clean thy tongue, lest thou provoke God more grievously.
...Having thus adorned ourselves, let us come to our King, and fall at His knees, not with the body only, but also with the mind. Let us consider whom we are approaching, and on whose behalf, and what we would accomplish. We are drawing nigh unto God, whom the seraphim behold and turn away their faces, not bearing His brightness; at sight of whom the earth trembles. We draw nigh unto God, "who dwelleth in the light, which no man can approach unto." And we draw nigh unto Him for deliverance from hell, for remission of sins, for escape from those intolerable punishments, for attaining to the Heavens, and to the good things that are there. Let us, I say, fall down before Him both in body and in mind, that He may raise us up when we are down; let us converse with all gentleness and meekness.1
1. St. Chrysostom, Ed. Philip Schaff, Nicene and Post-Nicene Fathers: Volume 10 [Peabody, MA: Hendrickson Publsihers Inc., 1995 reprint], pp. 319-20