Romans 15:20

Now it has been my ambition to preach the good news at places where Christ's name has never been heard, so that I would not be building on someone else's foundation.

2 Corinthians 10:13-16

But we will not boast beyond our proper boundaries [Note: This may mean that Paul was not attempting to exercise apostolic authority outside the parameters assigned to him by God], but will restrict our boasting to the area assigned to us by God as a field of service, which includes you people [there in Corinth].

1 Corinthians 3:9-15

For we are all fellow-workers in God's service; you people are God's farm land; [you are] God's building.

Ephesians 2:20-22

[You are] built on the foundation of the apostles and prophets [See I Cor. 12:28], with Christ Jesus Himself being the principal stone by which the entire building is aligned.

Treasury of Scripture Knowledge

Summary

Yea, so have I strived to preach the gospel, not where Christ was named, lest I should build upon another man's foundation:

Bible References

So

2 Corinthians 10:14
Now we are not going too far in claiming you as part of our outreach, since we were the first ones to come to you with the Gospel of Christ.

Build

1 Corinthians 3:9
For we are all fellow-workers in God's service; you people are God's farm land; [you are] God's building.
2 Corinthians 10:13
But we will not boast beyond our proper boundaries [Note: This may mean that Paul was not attempting to exercise apostolic authority outside the parameters assigned to him by God], but will restrict our boasting to the area assigned to us by God as a field of service, which includes you people [there in Corinth].
Ephesians 2:20
[You are] built on the foundation of the apostles and prophets [See I Cor. 12:28], with Christ Jesus Himself being the principal stone by which the entire building is aligned.