Acts of the Apostles 1:1-4 NLT
In my first book I told you, Theophilus, about everything Jesus began to do and teach until the day he was taken up to heaven after giving his chosen apostles further instructions through the Holy Spirit. During the forty days after he suffered and died, he appeared to the apostles from time to time, and he proved to them in many ways that he was actually alive. And he talked to them about the Kingdom of God.
Once when he was eating with them, he commanded them, “Do not leave Jerusalem until the Father sends you the gift he promised, as I told you before.
NLT: New Living Translation