CCC 664 Being seated at the Father’s right hand signifies the inauguration of the Messiah’s kingdom, the fulfillment of the prophet Daniel’s vision concerning the Son of man: “To him was given dominion and glory and kingdom, that all peoples, nations, and languages should serve him; his dominion is an everlasting dominion, which shall not pass away, and his kingdom one that shall not be destroyed.”1 After this event the apostles became witnesses of the “kingdom [that] will have no end”.2

1 Dan 7:14.
2 Nicene Creed.