6 And when this sound occurred, the multitude came together, and were confused, because everyone heard them speak in his own language. 7 Then they were all amazed and marveled, saying to one another, "Look, are not all these who speak Galileans? 8 And how is it that we hear, each in our own language in which we were born? 9 Parthians and Medes and Elamites, those dwelling in Mesopotamia, Judea and Cappadocia, Pontus and Asia, 10 Phrygia and Pamphylia, Egypt and the parts of Libya adjoining Cyrene, visitors from Rome, both Jews and proselytes, 11 Cretans and Arabs--we hear them speaking in our own tongues the wonderful works of God."
Matthew Henry's Commentary on Acts 2:6-11
Commentary on Acts 2:5-13
(Read Acts 2:5-13)
The difference in languages which arose at Babel, has much hindered the spread of knowledge and religion. The instruments whom the Lord first employed in spreading the Christian religion, could have made no progress without this gift, which proved that their authority was from God.