IN THE FIRST BOOK, Theophilus, I wrote about all that Jesus did and taught from the beginning, until the day when He was taken up to heaven, after giving instructions through the Holy Spirit to the apostles whom He had chosen. After He suffered, He also presented Himself alive to them by many convincing proofs, appearing to them during forty days and speaking about the Kingdom of God. While staying with them, He ordered them not to leave Jerusalem, but to wait there for the promise of the Father. “This,” He said, “is what you have heard from Me, for John baptized with water, but you will be baptized in the Holy Spirit not many days from now.” So when they had come together, they asked Him, “Lord, is this the time when You will restore the Kingdom to Israel?” He replied, “It is not for you to know the times or seasons that the Father has set by His own authority. But you will receive power when the Holy Spirit has come upon you, and you will be My witnesses in Jerusalem, in all Judea and Samaria, and to the ends of the earth.”
Saint John Chrysostom comments on Christ's appearance of His resurrection only to the apostles,
Why did Jesus appear only to the apostles? Because to the many it would have seemed a mere apparition, inasmuch as they did not understand the secret of the mystery. For the disciples themselves were at first incredulous and needed the evidence of actual touch with the hand, and of His eating with them. For this reason therefore, through the miracles done by the apostles, He renders the evidence of His resurrection unequivocal. All people thereafter should be certain that He was risen.