The disciplines speaking in tongues was a fulfilment of a prophecy by

The prophecy about speaking in tongues is mentioned in the book of Joel in the Bible. In Joel 2:28, it is written "And it shall come to pass afterward, that I will pour out my Spirit on all flesh; your sons and your daughters shall prophesy, your old men shall dream dreams, and your young men shall see visions." This verse is often understood as a prophecy about the outpouring of the Holy Spirit, which is believed by Christians to have happened on the day of Pentecost, as described in the book of Acts in the New Testament. On that day, the apostles and other followers of Jesus were filled with the Holy Spirit and began to speak in other tongues, as a sign of God's power and presence among them. In this way, the book of Joel is seen as foretelling the events of Pentecost, and the speaking in tongues is understood as a fulfillment of the prophecy in Joel 2:28.