en_tn_condensed/1co/15/10.md

the grace of God I am what I am

God's grace or kindness has made Paul as he is now.

his grace in me was not in vain

"because he was kind to me, I was able to do much good work"

the grace of God that is with me

Possible meanings are 1) this is literally true, and God actually did the work and kindly used Paul as a tool or 2) Paul is saying that God was kind to let Paul do the work and to make Paul's work have good results.