Verses with the word diligent in the New Testament (3 verses):

2 Corinthians 8:22
And we have sent with them our brother, whom we have oftentimes proved diligent in many things, but now much more diligent, upon the great confidence which I have in you.

Titus 3:12
When I shall send Artemas unto thee, or Tychicus, be diligent to come unto me to Nicopolis: for I have determined there to winter.

2 Peter 3:14
Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of him in peace, without spot, and blameless.