KJV:
I speak not by commandment, but by occasion of the forwardness of others, and to prove the sincerity of your love.
NASB:
I am not speaking this as a command, but as proving through the earnestness of others the sincerity of your love also.
KJV:
And we have sent with them our brother, whom we have oftentimes proved diligent in many things, but now much more diligent, upon the great confidence which I have in you.
NASB:
We have sent with them our brother, whom we have often tested and found diligent in many things, but now even more diligent because of his great confidence in you.
KJV:
Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
NASB:
Test yourselves to see if you are in the faith; examine yourselves! Or do you not recognize this about yourselves, that Jesus Christ is in you-- unless indeed you fail the test?
KJV:
But let every man prove his own work, and then shall he have rejoicing in himself alone, and not in another.
NASB:
But each one must examine his own work, and then he will have reason for boasting in regard to himself alone, and not in regard to another.
KJV:
That ye may approve things that are excellent; that ye may be sincere and without offence till the day of Christ;
NASB:
so that you may approve the things that are excellent, in order to be sincere and blameless until the day of Christ;
KJV:
But as we were allowed of God to be put in trust with the gospel, even so we speak; not as pleasing men, but God, which trieth our hearts.
NASB:
but just as we have been approved by God to be entrusted with the gospel, so we speak, not as pleasing men, but God who examines our hearts.