Psalm 118 Part 5 

As the cornerstone, he is now the bond of the building, holding Jew and Gentile in firm unity. This precious cornerstone binds God and man together in wondrous harmony, for he is both in one. He joins earth and heaven together, for he participates in each. He joins time and eternity together, for he was a man of few years, and yet he is the Ancient of Days. Wondrous cornerstone! Jesus was and will be exulted.  
It is hard to imagine Jesus singing this without tears in His eyes the night before His great rejection, suffering, and crucifixion. He would be ‘rejected,’ and He would ‘become the chief cornerstone.’ 

V23 – ‘This was the LORD’s doing; it is marvellous in our eyes:’ What can be more truly marvellous; that a person put to death as a criminal and laid in the grave, should then arise immortal, and become the head of a future redeemed and immortal congregation; He ascended into heaven, was invested with power, crowned with glory, and prepared a way for the sons of Adam to follow him into those mansions of eternal delight?  
What astonishment will then take hold upon those who refused his righteous claims? Then will they know that this is the Lord’s doing (v23); though it will be terrible in their eyes! All intelligent beings, even down to the devil and his cohort, shall at the second advent of our Lord, be obliged to confess that the stone which the builders refused has become the cornerstone, the foundation of a redeemed society. (Phil.2:10!) 

When Jesus quoted v22 (e.g.Matt.21:42), He did so in response to the praise and hosannas given to Him at what is called the triumphal entry. Since this psalm is prophetically connected with that event, ‘the day’ mentioned in v24 can be prophetically understood as the day Jesus formally entered Jerusalem as Messiah and King. This day was prophesied in Daniel.9:24-26. 

In the context of the open gates (v19), the coming into the city, and the arrangement of this psalm, we have the sense that this is a choral hosanna. Can you hear 12 men singing it as the prelude to Gethsemane?