Berean Study Bible
The one who saw it has testified to this, and his testimony is true. He knows that he is telling the truth, so that you also may believe.

King James Bible
And he that saw it bare record, and his record is true: and he knoweth that he saith true, that ye might believe.

American Standard Version
And he that hath seen hath borne witness, and his witness is true: and he knoweth that he saith true, that ye also may believe.

Darby Bible Translation
And he who saw it bears witness, and his witness is true, and he knows that he says true that ye also may believe.

Douay-Rheims Bible
And he that saw it, hath given testimony, and his testimony is true. And he knoweth that he saith true; that you also may believe.

English Revised Version
And he that hath seen hath borne witness, and his witness is true: and he knoweth that he saith true, that ye also may believe.

Young's Literal Translation
and he who hath seen hath testified, and his testimony is true, and that one hath known that true things he speaketh, that ye also may believe.