2 Corinthians 10:15-18

We do not go beyond our proper limit, boasting in the work of other men, but we have the hope that as your faith [in Christ and His divine power] continues to grow, our field among you may be greatly expanded [but still within the limits of our commission], so that we may preach the gospel even in the lands beyond you, but not to boast in work already accomplished in another one’s field of activity. However, “LET HIM WHO BOASTS BOAST IN THE LORD.” [Jer 9:24] For it is not he who commends and praises himself who is approved [by God], but it is the one whom the Lord commends and praises.