There are five places in the New Testament where speaking in tongues is referred to explicitly:

• Mark 16:17, which records the instructions of Christ to the apostles, including his description that "they will speak with new tongues" as a sign that would follow "them that believe" in him. Many scholars take Mk 16:8 as the original ending and believe the ending (Mk 16:9-20) was written later. (see Mark 16)

• Acts 2, which describes tongues-speaking occurring in Jerusalem at Pentecost.

• Acts 10:46, when the household of Cornelius in Caesarea spoke in tongues, and those present compared it to the tongues-speaking that occurred at Pentecost.

• Acts 19:6, when a group of approximately a dozen men spoke in tongues in Ephesus as they received the Holy Spirit while the apostle Paul laid his hands upon them.

• 1 Cor 14, where Paul discusses speaking in "various kinds of tongues" as part of his wider discussion of the gifts of the Spirit; his remarks shed some light on his own speaking in tongues as well as how the gift of speaking in tongues was to be used in the church.

Other verses by inference may be considered to refer to 'speaking in tongues', such as Romans 8:26 and Jude 21.

The biblical account of Pentecost in the second chapter of the book of Acts describes the sound of a mighty rushing wind and "divided tongues like fire" coming to rest on the apostles. The text further describes that "they were all filled with the Holy Spirit, and began to speak in unknown languages."