NET
16 so that we may preach the gospel in the regions that lie beyond you, and not boast of work already done in another person’s area.
Darby
16 to announce the glad tidings to that [which is] beyond you, not to be boasting in another's rule of things made ready to hand.
KJV
16 To preach the gospel in the [regions] beyond you, [and] not to boast in another man's line of things made ready to our hand.