Their reception of the Holy Spirit in the Upper Room, and their empowerment to speak in tongues, are recounted in Acts 2:1–6:[8] ¹When the day of Pentecost had come, they were all together in one place.

²And suddenly from heaven there came a sound like the rush of a violent wind, and it filled the entire house where they were sitting.

Henry Alford suggests that "we may safely decide for the former reference" (the sound from heaven) because the writer would have written "φωναί" (phōnai: plural) if the multiple voices spoken in tongues was intended.

The extended quotation from Joel 2:28–32 (LXX) is to support that this event is something predicted in Scripture, and it clarifies some points about the apostolic proclamation:[14] ²²"Men of Israel, hear these words: Jesus of Nazareth was a man attested to you by God with powerful works and wonders and signs, which God did through Him in your midst, as you yourselves know.

²⁸You have made known to me the ways of life; You will make me full of joy in Your presence.’ According to a Christian interpretation, verse 27 recalls the belief in the preservation of the mortal bodies of the saints, identified with the people whose souls weren't condemned to the Hell.

[17] It has also been seen as a prophecy of Jesus' Harrowing of Hell, while verse 26 would have predicted the final Resurrection of the flesh for which the "body also will rest in hope".

Furthermore, the paths of life of Acts 2:28 recall the more well known Jesus self-definition as being "the way, the truth, the life" (John 14:6, even using the same Greek words (respectively: hodous zōēs[18] and hodos, alētheia, zōē[19]) Verses 34 and 35 quote Psalms 110:1 to conclude saying: Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.

Then Peter said to them, "Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit."

A "mikveh" is a stepped immersion pool used by Jews for purification, before prayer or worship, to become ritually clean.

"[23] Traditional interpretation holds that the Descent of the Holy Spirit took place in the Upper Room, or Cenacle, on the day of Pentecost (Shavuot).

The other mention of an "upper room" is in Acts 1:13–14, the continuation of the Luke narrative, authored by the same biblical writer.