John 3:11 in the King James Version
Verily, verily, I say unto thee, We speak that we do know, and testify that we have seen; and ye receive not our witness.
Context
10 Jesus answered him, “Are you the teacher of Israel, and don’t understand these things?
11 Most certainly I tell you, we speak that which we know and testify of that which we have seen, and you don’t receive our witness.
12 If I told you earthly things and you don’t believe, how will you believe if I tell you heavenly things?