In Jesus' day Jews observed the Passover by singing or chanting six Psalms: 113 through 118. So when Matthew mentions that after the Last Supper they sang a hymn, we can be sure they were singing these Psalms.
It is interesting to read Psalm 118 and to think of Jesus singing it on His way to the Garden of Gethsemane.
It is one thing to say verse 18, "This is the day the Lord has made; let us rejoice and be glad in it" (Psalm 118:24) when all is well. But that is not the context for these words.
This is what Jesus sang just before this verse: "The stone the builders rejected has become the capstone; the Lord has done this, and it is marvelous in our eyes." Then He sings, "This is the day the Lord has made; let us rejoice and be glad in it."
What submission! He knew He was about to be the capstone the builders would reject. All His Father did was good in His eyes. He was going to the Garden of Gethsemane and could rejoice because it was His Father's plan. His Father had made this day and He was rejoicing.
Dear Jesus, You have taught us by example to rejoice always.
"Be joyful always; pray continually; give thanks in all circumstances, for this is God's will for you in Christ Jesus" (1 Thess. 5:16-18).