Judas betrays Jesus
Judas betrays Jesus because, as the keeper of the money, he had stolen some for his own use. He had few days earlier talked with the Priests about handing Jesus over to them. Now Jesus says Go and do what you must do. Remember Judas was one of the Twelve.
Judas was not planning for the Priests to kill Jesus.
Prophecy said one of the twelve would betray Jesus for thirty pieces of silver the cost of a slave.
Background Reading:
Luke 22:1-6
Judas Agrees to Betray Jesus
22Now the Feast of Unleavened Bread, called the Passover, was approaching, 2 and the chief priests and the teachers of the law were looking for some way to get rid of Jesus, for they were afraid of the people. 3 Then Satan entered Judas, called Iscariot, one of the Twelve. 4 And Judas went to the chief priests and the officers of the temple guard and discussed with them how he might betray Jesus. 5 They were delighted and agreed to give him money. 6 He consented, and watched for an opportunity to hand Jesus over to them when no crowd was present.
and
Matthew 26:14-16
Judas Agrees to Betray Jesus
14 Then one of the Twelve- the one called Judas Iscariot-went to the chief priests 15 and asked, "What are you willing to give me if I hand him over to you?" So they counted out for him thirty silver coins. 16 From then on Judas watched for an opportunity to hand him over.
Also read Matthew 26:20-25, Luke 22:21-23, John 13:22-30
More Information:
Judas
Judas went to the Priests about two days before the feast of Unleavened bread or Passover.
After the incident were Mary Anoints Jesus' feet. The second time Jesus was anointed for his burial by perfume this time at Simon the leper's house were the woman anointed Jesus' head.
Not unlike the first time where it was done by Mary at her house where she lived with Martha and Lazarus which was four days earlier, eg six days before the Passover. See:- Matthew 26:14-16, Mark 14:10-11, Luke 22:1-6, John does not mention this incident.
Judas at the last supper:- Matthew 26:20-30, Mark 14:17-26, Luke 20-23, John 13:2 & John 13:18-30
Judas helps arrest Jesus:- Matthew 26:47-56, Mark 14:46-54, Luke 22:47-48, John 18:2-11
Judas death:- Matthew 27:3-10, Acts 1:15-26
Also read:- Matthew 26:14-16, Mark 14:10
Judas (Greek form of Judah which means praise) came from the south of Israel while the rest of the disciples came from around where Jesus grew up.