ESV: I say this not as a command, but to prove by the earnestness of others that your love also is genuine.
NIV: I am not commanding you, but I want to test the sincerity of your love by comparing it with the earnestness of others.
NASB: I am not saying this as a command, but as proving, through the earnestness of others, the sincerity of your love as well.
CSB: I am not saying this as a command. Rather, by means of the diligence of others, I am testing the genuineness of your love.
NLT: I am not commanding you to do this. But I am testing how genuine your love is by comparing it with the eagerness of the other churches.
KJV: I speak not by commandment, but by occasion of the forwardness of others, and to prove the sincerity of your love.
NKJV: I speak not by commandment, but I am testing the sincerity of your love by the diligence of others.