15:2 and by which you are being saved, if you hold firmly to the message I preached to you – unless you believed in vain.
1 Korintus 15:10
15:10 But by the grace of God I am what I am, and his grace to me has not been in vain. In fact, I worked harder than all of them – yet not I, but the grace of God with me.
1 Korintus 15:58
15:58 So then, dear brothers and sisters, 1 be firm. Do not be moved! Always be outstanding in the work of the Lord, knowing that your labor is not in vain in the Lord.
1 tnGrk “brothers.” See note on the phrase “brothers and sisters” in 1:10.