Verses 3 to 8 of John 12. 

Then Mary took a twelve-ounce jar of expensive perfume made from essence of nard, and she anointed Jesus’ feet with it, wiping his feet with her hair. The house was filled with the fragrance. But Judas Iscariot, the disciple who would soon betray him, said, “That perfume was worth a year’s wages. It should have been sold and the money given to the poor.” Not that he cared for the poor—he was a thief, and since he was in charge of the disciples’ money, he often stole some for himself.

Jesus replied, “Leave her alone. She did this in preparation for my burial. You will always have the poor among you, but you will not always have me.”