2 Corinthians 1:7 grounds their mutual hope in shared suffering — the foundation for the mutual boasting on that day.

In 2 Corinthians 5:12, Paul gives them grounds to boast about him, echoing the mutual boasting in the day of the Lord.

In 2 Corinthians 9:2, Paul boasts to the Macedonians about the Corinthians' readiness — a concrete example of him boasting about them.

2 Corinthians 7:4 expresses great pride/boasting in them now — a present echo of the future boasting on that day.

1 Corinthians 1:8 similarly promises God will sustain believers to the end, guiltless on the day of our Lord Jesus Christ — reinforcing the eschatological hope.

In 1 Corinthians 15:31, Paul calls the Corinthians his pride in Christ — identical to the mutual boasting here.

Philippians 1:6 affirms God who began a good work will complete it on the day of Jesus Christ — same confidence in final perseverance.

Philippians 1:10 urges being pure and blameless for the day of Christ — the same goal of blamelessness on that day.

In Philippians 1:26, Paul says his coming gives them reason to glory in Christ — same mutual boasting theme.

In Philippians 2:16, Paul looks to the day of Christ as the occasion for his pride in them — same eschatological boast.

In Philippians 4:1, Paul calls them his joy and crown — equivalent to his boast in the Lord.

In 1 Thessalonians 2:19, Paul says the Thessalonians are his crown of boasting at Jesus' coming — exactly the same idea.

In 1 Thessalonians 2:20, Paul says 'you are our glory and joy' — a direct parallel to the mutual boasting here.

1 Thessalonians 3:13 prays for blameless hearts at the coming of the Lord — the same eschatological blamelessness.

In 1 Corinthians 3:21-23, Paul warns against boasting in people, while here he boasts in them as partners — complementary perspectives.