Genesis 11:1

And the whole earth had one language, and the same words.

Zephaniah 3:9

For then will I turn to the peoples a pure language, that they may all call upon the name of Jehovah, to serve him with one consent.

Acts 2:6

But the rumour of this having spread, the multitude came together and were confounded, because each one heard them speaking in his own dialect.

Isaiah 19:18

In that day shall there be five cities in the land of Egypt speaking the language of Canaan, and swearing by Jehovah of hosts: one shall be called, The city of Heres.

Treasury of Scripture Knowledge

Summary

And the whole earth was of one language, and of one speech.

Bible References

Was

Isaiah 19:18
In that day shall there be five cities in the land of Egypt speaking the language of Canaan, and swearing by Jehovah of hosts: one shall be called, The city of Heres.
Zephaniah 3:9
For then will I turn to the peoples a pure language, that they may all call upon the name of Jehovah, to serve him with one consent.
Acts 2:6
But the rumour of this having spread, the multitude came together and were confounded, because each one heard them speaking in his own dialect.