In 2 Corinthians 10:13, Paul explains he boasts only within God's assigned sphere — the basis for his claim in the next verse that he reached them first.

2 Corinthians 3:1-3 says the Corinthians themselves are Paul's letter of recommendation, supporting his claim in 10:14 that he was first to reach them.

1 Corinthians 3:10 says Paul laid the foundation in Corinth — directly parallel to his claim of being first to bring the gospel there.

1 Corinthians 4:15 calls Paul the Corinthians' father through the gospel — reinforcing his role as the one who first brought them to faith.

1 Corinthians 9:1 asks if they are not his workmanship — supporting his claim of being the one who reached them first.

1 Corinthians 9:2 calls them the seal of his apostleship — directly tied to his pioneering work in reaching Corinth first.

In Romans 15:20, Paul states his ambition to preach where Christ is not named — explaining his claim here to have first reached Corinth with the gospel.

In 1 Corinthians 3:6, Paul says he planted the church in Corinth — confirming his claim here to have been the first to bring the gospel to them.

1 Corinthians 3:5 calls Paul a servant through whom Corinthians believed — echoing his role as first preacher to them.

Romans 15:18 speaks of Christ's work through Paul among Gentiles, complementing his insistence that he pioneered the gospel to Corinth.