During his explanation of his humble service, Jesus says that not ever disciple present is a true follower. One will betray him in order to fulfill scripture (13:18). Since Jesus uses a text which may not have been seen as explicitly messianic, we have an opportunity to see how a scriptural citation works in the context of Jesus’ ministry. Jesus cites Psalm 41:9 as fulfilled in Judas’s betrayal.
In the context of this Psalm, The psalmist is lamenting the oppression he faces from enemies, but more specifically, his betrayal by all of his supporters. It is possible the Psalm refers to the rebellion of Absalom against David, although David’s psalms often speak of betrayal. Since the Psalm ends with the writer restored to the presence of God forever, it is possible that the whole context of the Psalm is the betrayal of the king and the ultimate vindication of the King.
Mephiboseth, the son of Jonathan, ate at David’s table and was implicated in Absalom’s rebellion. It is not just that David’s supporters have shifted allegiance to the rebel Absalom, but even those who were his closest advisors have betrayed him. In an ancient near-eastern context, if David has shown hospitality by sharing meals with someone, they are under his protection. To betray that protection is the height of disloyalty (in Mephbosheth’s case, it is treason!)
The verse prior to the one quoted by Jesus is remarkable. The enemies mock the king, saying that he has suffered a “deadly thing,” a disaster so great that he cannot possible rise (Ps 49:8). This may refer to a disease which threatens to kill the king, proving that he was not God’s chosen one in the first place. Yet the psalm ends with a vindication of the king. He does in fact rise up from his deadly defeat and is place in the presence of God.
The point of the allusion to Psalm 41:9 is therefore to highlight the treason of one of Jesus’ disciples. The betrayer has not just shared Jesus’ food and enjoyed his protection, he has witnessed the seven signs and heard Jesus’ teaching. By betraying Jesus, this disciple is rejecting Jesus as the Messiah, the son of God.
In fact, it may look (for a short time) like the betrayer was right, Jesus is not the son of God. He has succumbed to death, proving that he is not the Messiah! Yet, like the psalm he quoted, Jesus will be restored to the presence of God when God raises him from the dead.
By looking at the larger context of the Psalm, we see that Jesus may have had more in mind that a prediction of a betrayer. He was predicting his eventual vindication at the time of the resurrection.