Thus, in his speech before Herod and Festus, he says that he bears witness to God's truth, both to small and great, saying nothing except what the Prophets and Moses said would come to pass (cf. Acts 26:22).
He directs thoughts to the same point here, so as to open a path for his word into the hearts of both Jews and Gentiles. A Jew could not even hear anything new.
On the contrary, he became an obedient lamb when he was addressed with the word of his fathers and the Prophets. This could not incline a Gentile to faith, for it was not his fathers who had foretold it.
Yet he could not fail to honor a teaching so long ago foretold and prefigured. According to the common understanding of all, foretelling is the work of God. The fulfillment of what was foretold is also God's work.
Whoever proclaims such a teaching cannot himself be outside the realm of God. At once he binds others to faith.
Moreover, among the Gentiles, as Suetonius and Tacitus testify, there were then rumors that teachers would soon come forth from Judea and subject the whole world to their teaching.
When they heard the Apostle's words, "which He promised beforehand," they could not help thinking, "Surely this is what the rumor among us concerns." Having thought this, they could not help saying to themselves, "We must listen, even if we do not believe at once."
Saint Chrysostom says concerning this: "Do not leave unnoticed why this was foretold so long beforehand. If God prepares something great, He foretells it long in advance, so as to attune the hearing to receive it when it is fulfilled."
The Apostle says that the gospel was promised. So indeed it was. Moses gave the Law, but immediately said, "See, God will send us another Prophet. Him you shall hear."
The Prophets urged the people to be faithful to the Law that had been given. At the same time, they said that God would give them another law, one that would be inscribed upon their hearts.
Saint David foresaw how the Lord would give the word to those who proclaim good tidings with great power (Ps 67:12). Saint Isaiah also prefigured the beautiful feet of those who proclaim good tidings (cf. Is 52:7).
Yet the gospel is good tidings precisely because it announces good things. Therefore the promise of the gospel was a promise of good things for the human race.
That is, it was not only a good word that was promised, but the good deed itself. This promise truly began immediately after the Fall.
Throughout all the time that followed, it did not cease, but continued without interruption. It disclosed in every detail the good work that was to be accomplished.
The events of the Gospel are all prefigured in the Old Testament as in a painting. Men enlightened by God knew that something wondrous and great was being prepared.
They desired to see that event personally, but did not see it (cf. Mt 13:17). Only Abraham was granted to see all this in a certain special manner. "He saw it and rejoiced" (Jn 8:56).
For this foretelling, God raised up Prophets, enlightened their minds by the Holy Spirit, and they saw the future and spoke of what they had seen. "And they not only spoke, but also wrote what they spoke" (Saint Chrysostom).
Thus the gospel was promised beforehand through the Prophets in the Holy Scriptures.