Theophylact of Bulgaria
But although the four Evangelists record the anointing by a woman, there were two women and not one; one described by John, the sister of Lazarus; it was she who six days before the Passover anointed the feet of Jesus; another described by the other three Evangelists. Nay, if you examine, you will find three; for one is described by John, another by Luke, a third by the other two. For that one described by Luke is said to be a sinner and to have come to Jesus during the time of His preaching; but this other described by Matthew and Mark is said to have come at the time of the Passion, nor did she confess that she had been a sinner.
Or as is said in Greek, of pistic nard, that is, faithful, because the ointment of the nard was made faithfully and without counterfeit. (Matt. 26:2)
Or else, it appears to be aptly implied that many disciples murmured against the woman, because they had often heard our Lord talking of alms. Judas, however, was indignant, but not with the same feeling, but on account of his love of money, and filthy gain; wherefore John also records him alone, as accusing the woman with a fraudulent intent. But he says, They murmured against her, meaning that they troubled her with reproaches, and hard words. Then our Lord reproves His disciples, for throwing obstacles against the wish of the woman. Wherefore it goes on: And Jesus said, Let her alone, why trouble ye her? For after she had brought her gift, they wished to prevent her purpose by their reproaches.
For she is come aforehand as though led by God to anoint my body, as a sign of my approaching burial; by which He confounds the traitor, as if He said, With what conscience canst thou confound the woman, who anoints my body to the burial, and dost not confound thyself, who wilt deliver me to death? But the Lord makes a double prophecy; one that the Gospel shall be preached over the whole world, another that the deed of the woman shall be praised. Wherefore it goes on: Verily I say unto you, Wheresoever this gospel shall be preached throughout the whole world, this also that she hath done shall be spoken of for a memorial of her.