While they prayed, the Holy Spirit came

Lord, baptize us with the Holy Spirit and fire.

"When all the people were baptized, it came to pass that Jesus also was baptized; and while He prayed, the heaven was opened.  And the Holy Spirit descended in bodily form like a dove upon Him, and a voice came from heaven which said, “You are My beloved Son; in You I am well pleased.”   (Luke 3:21-22 NKJV)

While they prayed...

14 They all met together and were constantly united in prayer, along with Mary the mother of Jesus, several other women, and the brothers of Jesus.
(Acts 1:14 NLT)

"On the day of Pentecost all the believers were meeting together in one place.  Suddenly, there was a sound from heaven like the roaring of a mighty windstorm, and it filled the house where they were sitting.  Then, what looked like flames or tongues of fire appeared and settled on each of them.  And everyone present was filled with the Holy Spirit and began speaking in other languages, as the Holy Spirit gave them this ability.
(Acts 2:1-4 NLT)

"O God, whose Only Begotten Son has appeared in our very flesh, grant, we pray, that we may be inwardly transformed through Him whom we recognize as outwardly like ourselves.  Who lives and reigns with You in the unity of the Holy Spirit, one God, forever and ever.  Amen. "

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