So then, brothers, stand firm and hold to the teachings we passed on to you, whether by word of mouth or by letter. 
2 Thessalonians 2:15 (NIV)

We must pay more careful attention, therefore, to what we have heard, so that we do not drift away.
Hebrews 2:1 (NIV)

So then, those who suffer according to God's will should commit themselves to their faithful Creator and continue to do good.  
1 Peter 4:19 (NIV)