What does the Bible say about the Holy Spirit's role on Pentecost?

The prophecy in Joel 2:28-32 foretells an outpouring of the Holy Spirit on all flesh, which is fulfilled on the day of Pentecost as described in Acts 2. This moment marks the transition from the Old Covenant, where the Spirit was given selectively, to the New Covenant, where every believer has the Holy Spirit indwelling them. This event signifies a new relationship between God and His people, highlighting that all believers—regardless of social status—receive the Spirit, enabling them to prophesy and speak the truth of the gospel.