Matthew 26:73

But soon afterwards those who were standing by came up and said to Peter: "You also are certainly one of them; why, your very way of speaking proves it!"

Luke 22:59-60

About an hour later another man declared positively: "This man also was certainly with him. Why, he is a Galilean!"

John 18:26-27

One of the High Priest's servants, a relation of the man whose ear Peter had cut off, exclaimed: "Did not I myself see you with him in the garden?"

Treasury of Scripture Knowledge

Summary

And after a while came unto him they that stood by, and said to Peter, Surely thou also art one of them; for thy speech bewrayeth thee.

Bible References

Surely

Luke 22:59
About an hour later another man declared positively: "This man also was certainly with him. Why, he is a Galilean!"
John 18:26
One of the High Priest's servants, a relation of the man whose ear Peter had cut off, exclaimed: "Did not I myself see you with him in the garden?"