In 1 Corinthians 15:3, Paul states the gospel he delivered — the death of Christ — which is the content of the preaching he references in v.11.

1 Corinthians 15:4 gives the specific resurrection content that Paul says all apostles preach here.

1 Corinthians 15:2 connects this preaching to salvation, directly tying to the belief Paul mentions here.

1 Corinthians 2:2 shows Paul's core preaching on Christ crucified, complementing the resurrection focus here.

Philippians 1:18 echoes Paul's joy that Christ is preached regardless of who does it, mirroring his attitude here.

2 Timothy 2:8 summarizes Paul's gospel as Jesus raised from the dead, exactly the message preached here.