1 Corinthians 15:11

11 Whether, then, it is I or they, this is what we preach, and this is what you believed.

Read 1 Corinthians 15:11 Using Other Translations

Therefore whether it were I or they, so we preach, and so ye believed.
Whether then it was I or they, so we preach and so you believed.
So it makes no difference whether I preach or they preach, for we all preach the same message you have already believed.