Ps 117:24

“We must keep the law regarding Easter in such a way that we do not observe the fourteenth as the day of the resurrection; that day or one very close to it is the day of the passion, because the feast of the resurrection is kept on the Lord's day. Moreover, we cannot fast on the Lord's day; fasting on this day is what we criticize in the Manichaeans. One shows disbelief in the resurrection of Christ if he proposes a law that we fast on the day of the resurrection, since the law says that the Passover should be eaten with bitterness, that is, with sorrow because the author of our salvation was slain by humanity's great sacrilege. On the Lord's day the prophet bids us rejoice, saying, "This is the day that the Lord has made; let us be glad and rejoice at it."”

“"This is the day which the Lord hath made" (ver. 24). This man remembereth that he had said in former Psalms, "Since He hath inclined His ear unto me, therefore will I call upon Him as long as I live;" making mention of his old days; whence he now saith, "This is the day which the Lord hath made;" that is, wherein He hath given me Salvation. This is the day whereof He said, "In an acceptable time have I heard thee, and in a day of Salvation have I helped thee;" that is, a day wherein He, the Mediator, hath become the head Stone of the corner. "Let us rejoice," therefore, "and be glad in Him."”

“What we have sung to God: This is the day which the Lord has made, hence let us speak of what the Lord has given. Here the Prophetic Scripture surely wanted us to understand something. That day which is not common, not conspicuous to the eyes of the flesh! It is not that day which rises and sets but the day which could know its dawn, not its setting! Let us see what the same Psalm previously said: The stone which the builders rejected, this has become the cornerstone. By the Lord has this been done, it is marvelous in our eyes. And it continues: This is the day which the Lord has made. Let us take the beginning of this day from the cornerstone. Who is the cornerstone which the builders rejected if not the Lord Christ whom the Jewish teachers rejected? For the experts of the Law, the teachers of the Jews, rejected Him saying: This one is not from God who loosens the Sabbath. You have already said: This one is not from God who loosens the Sabbath. The stone which the builders rejected, this one has become the cornerstone. How as the cornerstone? Why is Christ called the cornerstone? Because every corner unites two walls from different angles. The Apostles came from the circumcision, they came from the people of the Jews, they also came from those crowds which preceded and followed His beast, saying what is in this same Psalm: Blessed is he who comes in the name of the Lord; from there came so many churches of which the Apostle Paul says: I was unknown by face to the churches of Judea which are in Christ, but they only heard that he who formerly persecuted us now preaches the faith which he once destroyed and they glorified God in me, Jews but adhering to Christ like the Apostles, coming and believing in Christ and making one wall. The other part remained, the Church coming from the Gentiles. They found each other; peace in Christ, unity in Christ who made both one. This is the day which the Lord has made. Consider the whole day as the head and the body, the head Christ, the body the Church. This is the day which the Lord has made.”

“"And he summoned the twelve," the text says. After the long centuries of dreadful night, the eternal day, our Christ, shone forth. The world had long awaited the splendor of his dawning. In the case of his twelve apostles he desired to signify the twelve hours of this day. The blessed psalmist saw this day in spirit when he sang, "This is the day that the Lord has made; let us be glad and rejoice in it." Consequently, the apostle, too, calls the believers children of light and of faith: "You are children of the light and children of the day."”