It was now two days before the Festival of Passover and Unleavened Bread. The chief priests and the teachers of the Law were looking for a way to arrest Jesus secretly and put him to death. 1
References for Mark 14:1
14.1 Ex 12.1-27.
"We must not do it during the festival," they said, "or the people might riot."
Jesus was in Bethany at the house of Simon, a man who had suffered from a dreaded skin disease. While Jesus was eating, a woman came in with an alabaster jar full of a very expensive perfume made of pure nard. She broke the jar and poured the perfume on Jesus' head. 2
References for Mark 14:3
14.3 Lk 7.37, 38.
Some of the people there became angry and said to one another, "What was the use of wasting the perfume?
It could have been sold for more than three hundred silver coins and the money given to the poor!" And they criticized her harshly.
But Jesus said, "Leave her alone! Why are you bothering her? She has done a fine and beautiful thing for me.
You will always have poor people with you, and any time you want to, you can help them. But you will not always have me. 3
She did what she could; she poured perfume on my body to prepare it ahead of time for burial.
Now, I assure you that wherever the gospel is preached all over the world, what she has done will be told in memory of her."
Then Judas Iscariot, one of the twelve disciples, went off to the chief priests in order to betray Jesus to them.
They were pleased to hear what he had to say, and promised to give him money. So Judas started looking for a good chance to hand Jesus over to them.