John Gill Commentary Matthew 23:26

"Thou blind Pharisee, cleanse first the inside of the cup and of the platter, that the outside thereof may become clean also." — Matthew 23:26 (ASV)

You blind Pharisee
Well might Christ call such an one a blind Pharisee, who was so scrupulously careful to cleanse his cup and platter; and yet made no conscience of filling them with what was gotten in an unjust way, and so defiled himself and them:

cleanse first that which is within the cup and platter, that the
outside of them may be clean also :
get food and drink in an honest way, remove all extortion and oppression out of your hands, and luxury and intemperance from your table; and so shall the outward cleanness of your cup and dish, be no reproach unto you, or testimony against you, of your hypocrisy.

So the great concern of all men should be, inward purity; that their hearts be purified by faith in the blood of Christ, and sprinkled from an evil conscience by the same; that principles of grace and holiness be formed in them by the Spirit of God; and then their outward lives and conversations being influenced thereby, will be honourable and agreeable to their professions. Otherwise, an external reformation, or an outward show of holiness, and bare pretensions to it, without internal grace, will never be of any avail in the sight of God.