Luke 24:49

“And behold, I send forth the promise of my Father on you, but tarry you in the city, until you be clothed with power from on high.”

But before they can do this they will need exceptional power, that which the Father has promised them, the drenching with the Holy Spirit (Luke 3:6), power from on High. In Luke the promise was made from the beginning, and later confirmed (Luke 11:13), but in John it was also clarified and expanded (John 7:38; John 14:16; John 14:26; John 15:26; John 16:7). There may, however, also here be a reference o the Old Testament promises of the Spirit in Isaiah 44:1; Ezekiel 36:25; Ezekiel 37:9; Joel 2:28 as cited in Acts 2:18)

This exceptional power came in two stages. Firstly in the Upper room it came to the Apostles alone as their eyes were opened to understand the Scriptures, and they received the Spirit of truth from Jesus ready for the task ahead, through Whose direction they would offer forgiveness to all who believed and come within the range of God's mercy (John 20:23). And then it would come on the whole body of disciples, forming them into the new congregation of the new Israel at Pentecost (Matthew 16:18; Acts 1:6; Acts 2:1), from where they would go out to proclaim the word of the Kingly Rule of God to the world.