1 Corinthians 15:8
And last of all he was seen of me also, as of one born out of due time.
Cross-reference
In 1 Corinthians 9:1, Paul defends his apostleship by asserting he has seen the Lord, directly linking to the appearance on the Damascus road.
Acts 9:3-5 recounts Jesus appearing to Paul on the Damascus road, the event Paul references as his resurrection appearance.
Acts 9:17 records Ananias confirming that Jesus appeared to Paul, corroborating Paul's claim of a post-resurrection appearance.
Acts 22:14 recounts Ananias' statement that Paul was chosen to see the Righteous One — the same Christophany as here.
Acts 26:16 records Christ's commission to Paul on the Damascus road — the very appearance Paul calls his untimely birth.
In Acts 9:27, Barnabas confirms Paul's encounter with the risen Lord, validating the resurrection appearance Paul mentions here.