John Calvin Commentary Matthew 26:12

"For in that she poured this ointment upon my body, she did it to prepare me for burial." — Matthew 26:12 (ASV)

She has done it to bury me. By these words Christ confirms what we have said, that the precious ointment was not valued by him on account of its odor, but solely in reference to his burial. It was because he wished to testify by this symbol, that his grave would yield a sweet odor, as it breathed life and salvation through the whole world.

Accordingly, we are told by John (John 12:7) that Christ praised Mary for having reserved that anointing until the day of his burial. But since the truth of this figure has been made fully apparent, and since Christ, in departing from the sepulcher, perfumed not one house, but the whole world, by the life-giving odor of his death, it would be childish to repeat an action for which no reason and no advantage could be assigned.