8 I am not commanding you, but I want to test the sincerity of your love by comparing it with the earnestness of others.

Read 2 Corinthians 8:8 Using Other Translations

I speak not by commandment, but by occasion of the forwardness of others, and to prove the sincerity of your love.
I say this not as a command, but to prove by the earnestness of others that your love also is genuine.
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.