1 Corinthians 15:11

but whether I or they labour'd most, this is what we preach, and this is what you believed.

1 Corinthians 2:2

for I did not think I was to have any other knowledge among you, than that of Christ, a crucified saviour.

1 Corinthians 15:3-4

I acquainted you chiefly with what I received myself, that Christ died for our sins, as the scriptures foretold:

Treasury of Scripture Knowledge

Summary

Therefore whether it were I or they, so we preach, and so ye believed.

Bible References

General references

1 Corinthians 15:3
I acquainted you chiefly with what I received myself, that Christ died for our sins, as the scriptures foretold:
1 Corinthians 2:2
for I did not think I was to have any other knowledge among you, than that of Christ, a crucified saviour.