Genesis 11:1

So it came to pass that, all the earth, was of one manner of speech, - and of one stock of words.

Zephaniah 3:9

Surely, then, will I turn unto the peoples a lip made pure, - that they all may call on the name of Yahweh, may serve him with one consent.

Acts 2:6

And this sound occurring the throng came together and was thrown into confusion, because each one severally heard in his own language them who were speaking;

Isaiah 19:18

In that day, shall there be five cities in the land of Egypt Speaking the language of Canaan, And swearing unto Yahweh of hosts, - The city of destruction, shall be the name of one!

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 unto Yahweh of hosts, - The city of destruction, shall be the name of one!
Zephaniah 3:9
Surely, then, will I turn unto the peoples a lip made pure, - that they all may call on the name of Yahweh, may serve him with one consent.
Acts 2:6
And this sound occurring the throng came together and was thrown into confusion, because each one severally heard in his own language them who were speaking;