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.
Berean Standard Bible (BSB)
He who has seen has testified, and his testimony is true. He knows that he tells the truth, that you may believe.
World English Bible (WEB)
And{G2532} he that saw{G3708}{(G5761)} it bare record{G3140}{(G5758)}, and{G2532} his{G846} record{G3141} is{G2076}{(G5748)} true{G228}: and he{G2548} knoweth{G1492}{(G5758)} that{G3754} he saith{G3004}{(G5719)} true{G227}, that{G2443} ye{G5210} might believe{G4100}{(G5661)}.
Strong's King James
(35) The one seeing, has testified and his testimony is firm-truth, he knows that he's telling the firm-truth so that you also may believe!
The F.O.G
The F.O.G Message
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.
Young's Literal Translation