“It is not for you to know the times or seasons that the Father has established by his own authority. But you will receive power when the Holy Spirit comes upon you, and you will be my witnesses in Jerusalem, throughout Judea and Samaria, and to the ends of the earth.” When he had said this, as they were looking on, he was lifted up, and a cloud took him from their sight. While they were looking intently at the sky as he was going," Acts 1:1-11
Readings for the Ascension: https://bible.usccb.org/bible/readings/052922-ascension.cfm