Jesus is in the upper room celebrating His last Passover with His disciples. During the supper Jesus assumed the role of a servant and washed the feet of the disciples (Joh 13:1-17), and the disciples argued again about which of them was the greatest (Luk 22:24-27; cf. Luk 9:46-48, Mat 20:20,24-27). Jesus also taught them that unlike the first time He sent them out, they would now need a money belt and a sword (Luk 22:35-36), and spoke many other things to them that only John many years later came to understand as important to share in His gospel. However, the two things that Matthew and Mark recorded as most significant to them and their purpose in writing at the time they did was Jesus’ announcement that it was one of them who would betray Him, and His institution of the Lord’s Supper.
What is the last thing of importance that both report as happening before they went out to the Mount of Olives? See Mat 26:30, Mar 14:26. What hymn did they sing? Recall that at the beginning of the Passover meal the first two of the Hallel Psalms 113-118 were sung after drinking the first cup of wine that was shared. Following the fourth cup, the cup of praise or hallel, that Jesus likely did not drink (Mat 26:29), the remaining Psalms 115-118 were sung; cf. Psa 116:13. Also recall that the Hallel Psalms were sung as songs of joy and praise not just at Passover, but also at Pentecost, Tabernacles, Hanukkah, and the new moons, so that all Jews would have known these psalms by heart, having sung them regularly all their lives. As we have also seen, the very last words of this hymn in Psa 118:22-26 were prominent in Jesus’ triumphal entry and ministry over the previous few days: The shout of hosanna by the crowds in Mat 21:9 is a transliteration of the Hebrew aN” h[‘yviAh from Psalm 118:25-26 that means literally save now, I/we beseech thee, and is related to Jesus’ name in Hebrew (Yeshua, cf. Joshua). In Jesus’ parable of the landowner to the religious leaders in Mat 21:42 He quotes from Psa 118:22-23, “The stone which the builders rejected, this became the chief corner stone; this came about from the Lord, and it is marvelous in our eyes.” And the very last words He spoke to the religious leaders before forsaking them and the temple in Mat 23:39 was that they would no longer see Him until they say, “Blessed is He who comes in the name of the Lord”, quoting from Psa 118:26—which they themselves would be singing the next day immediately after Jesus had died on the cross as they celebrated their own Passover. In this light, what is the significance of the words in Psa 118:27 to what was about to unfold and take place over the next day? Cf. Isa 53:4-6,8,10-12. Considering so great a salvation wrought for us by God, and at such a cost, what is the appropriate response expressed in the remaining verses of the hymn? See Psa 118:28-29.
As Matthew and Mark who wrote first are the most Jewish of the gospels, why is it perhaps not surprising in their emphasis of Jesus as the fulfillment of God’s promised Messiah who would save His people from their sins, that after reporting that Jesus would not drink again from the fruit of the vine (which their Jewish readers would have understood as the fourth cup), they simply reported that they sang a hymn (which their readers would have been completely familiar with and understood the significance of the hymn’s climax in Psa 118:22-29 to what they were writing of God’s salvation), and then went out to the Mount of Olives where God’s promises would immediately unfold? In regard to that salvation for which they hoped, how much more encompassing is salvation from sin than salvation from any other type of oppression, such as that which the Jews were experiencing under the Romans? Whereas deliverance from sin ultimately manifests itself in deliverance from such oppressions as even worldly conquerors are themselves conquered by the Prince of Peace, does deliverance from such oppressions alone ever truly provide a complete and lasting deliverance from oppression without also delivering from sin? Why not? See Joh 8:34-36; cf. Jdg 2:11-23, 3:7-8,12, 4:1-2, 6:1, etc… Considering the extent to which God went to communicate this truth by means not only of the prophetic word but of their customs that would be ingrained within them, how powerful and deceitful must those chains of sin be that hold people in bondage?