What is the meaning of Matthew 23:25-26?

25 Woe unto you, scribes and Pharisees, hypocrites! for ye make clean the outside of the cup and of the platter, but within they are full of extortion and excess. 26 Thou blind Pharisee, cleanse first that which is within the cup and platter, that the outside of them may be clean also. (Matthew 23:25-26 KJV)

William Burkitt’s Commentary

Our Saviour doth not here condemn their legal, or traditional washing of pots of cups, or any external decency and cleanliness in conversation; but his design is to shew them the vanity of outward purity, without inward sancity, and to convince them of the necessity of cleansing the heart, in order to the purifying and reforming the life: plainly intimating,

1. That men’s lives could no be so bad, if their hearts were not worse, all the obliquity fo their lives proceeding from the impurity of their hearts and natures.

2. That an holy heart will be accompanied with an holy life. A man may be outwardly pure, and yet inwardly filthy; but he that has a pure heart will live a pure and holy life. Cleanse that which is within the cup, that the outside may be clean also.