William Burkitt on Matthew 26:8

That is, when Judas, and some other disciples whom he had influenced, saw this action, they murmured; particularly Judas blamed this holy woman for needless prodigality, and did tacitly reflect upon Christ himself, for suffering that wasteful expence. O! how doth a covetous heart think everthing too good for Christ: he that sees a pious action well done, and seeks to undervalue it, show himself possessed with a spirit of envy. Judas's invidious spirit makes him censure an action which Christ highly approved.

Learn thence, That men who know not our hearts, may through ignorance or prejudice, censure and condemn those actions which God doth commend and will graciously reward. Happy for this poor woman that she had a more righteous judge to pass sentence upon her action than wicked Judas!