And we have seen and testify that the Father has sent his Son to be the Savior of the world. (NIV)
And [besides] we ourselves have seen (have deliberately and steadfastly contemplated) and bear witness that the Father has sent the Son [as the] Savior of the world. (AMP)
And we have seen and do testify that the Father sent the Son to be the Saviour of the world. (KJV)