God has not given us a spirit of fear, he has given us a spirit of power and love and self-control
2 Timothy 2:1.

Very often in scripture, the Holy Spirit is associated with the power of God. In Lukes version of the gospel, he tells us this:

And while staying with them he told them to not leave Jerusalem, but to wait for the promise of the Father, which, he said, you heard from me, for John baptized with water, but before many days you shall be baptized with the Holy Spirit. So when they had come together, they asked him, Lord, will you at this time restore the kingdom to Israel? He said to them, It is not for you to know times or seasons which the Father has fixed by his own authority. But you shall receive power when the Holy Spirit has come upon you; and you shall be my witnesses in Jerusalem and in all Judea and Samaria and to the end of the earth.

The disciples were concerned about the restoration of the kingdom of Israel. But Jesus told them that they should not be concerned about this. Instead, Jesus gave them their mission to be his witnesses AFTER the Holy Spirit has come on them.