Original Verse:
2nd Thessalonians Chapter 2 Verse 15So then, brothers, stand firm, and hold the traditions which you were taught by us, whether by word, or by letter.

Reference Verses:
1st Corinthians Chapter 11 Verse 2Now I praise you, brothers, that you remember me in all things, and hold firm the traditions, even as I delivered them to you.
1st Corinthians Chapter 16 Verse 13Watch! Stand firm in the faith! Be courageous! Be strong!