She hath done what she could - She has showed the highest attachment in her power; and it was, as it is now, a sufficient argument against there being any "real" waste, that it was done for the honor of Christ. See this passage explained in the notes at Matthew. 26:1-16.

To anoint my body to the burying - Εις τον ενταφιασμον, against, or in reference to, its embalmment, thus pointing out my death and the embalmment of my body, for the bodies of persons of distinction were wrapped up in aromatics to preserve them from putrefaction. See on Matthew 26:12 (note).

(4) She hath done what she could: she is come aforehand to anoint my body to the burying.
(4) This woman, by the secret influence of the Spirit, anoints Christ, and thus sets before men's eyes his death and burial which were at hand.

She hath done what she could,.... What she had in her heart, and in the power of her hands to do; she hath done according to her ability, and her good will; and if she had not done it now, she could not have done it at all.
She is come aforehand to anoint my body to the burying; or, "as if it was to bury me", as the Syriac version renders it. Christ signifies by this, that he should shortly die, and that this woman came before hand to anoint him, and, as it were, to perform the funeral rites before he was dead; it being revealed to her by the Spirit, that Jesus would quickly die, and she should not be able to perform this good work when dead, and therefore came to do it before; or, at least, she was directed by the Spirit of God, because she would be prevented doing it afterwards; See Gill on Matthew 26:12.

She hath done what she could--a noble testimony, embodying a principle of immense importance.
she is come aforehand to anoint my body to the burying--or, as in John (John 12:7), "Against the day of my burying hath she kept this." Not that she, dear heart, thought of His burial, much less reserved any of her nard to anoint her dead Lord. But as the time was so near at hand when that office would have to be performed, and she was not to have that privilege even after the spices were brought for the purpose (Mark 16:1), He lovingly regards it as done now. "In the act of love done to Him," says OLSHAUSEN beautifully, "she has erected to herself an eternal monument, as lasting as the Gospel, the eternal Word of God. From generation to generation this remarkable prophecy of the Lord has been fulfilled; and even we, in explaining this saying of the Redeemer, of necessity contribute to its accomplishment." "Who but Himself," asks STIER, "had the power to ensure to any work of man, even if resounding in His own time through the whole earth, an imperishable remembrance in the stream of history? Behold once more here the majesty of His royal judicial supremacy in the government of the world, in this, 'Verily I say unto you.'"