6 And when this sound came to their ears, they all came together, and were greatly surprised because every man was hearing the words of the disciples in his special language. 7 And they were full of wonder and said, Are not all these men Galilaeans? 8 And how is it that every one of us is hearing their words in the language which was ours from our birth?
Matthew Henry's Commentary on Acts 2:6-8
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.