Acts 1:4–8

Before going up to heaven, Jesus promises power so they can be his witnesses

4And while gathered together with them, he ordered them not to leave Jerusalem, but to wait for the promise of the Father, “which you heard from me;

5for John immersed in water, but you will be immersed in the Holy Spirit not many days from now.”

6So those who had come together were asking him, saying, “Lord, are you restoring the kingdom to Israel at this time?”

7He said to them, “It is not for you to know times or seasons that the Father has set by his own authority;

8but you will receive power when the Holy Spirit comes upon you, and you will be my witnesses both in Jerusalem and in all Judea and Samaria, and to the end of the earth.”

Study it word by word

In its context

2until the day on which he was taken up, after giving instructions through the Holy Spirit to the apostles whom he had chosen;

3to them he also presented himself alive after his suffering by many convincing proofs, appearing to them over forty days and speaking of the things concerning the kingdom of God.

…

9And having said these things, as they were watching, he was lifted up, and a cloud took him out of their sight.

10And as they were gazing into heaven while he was going, look, two men stood by them in white clothing,

Read all of Acts 1

Its words in the original

The Holy Spirit