1 Timothy 4:16
Be on your guard as to yourself and your teaching. Persevere in these things; for by doing this you will make certain your own salvation and that of your hearers.
Ephesians 5:12
for the things which are done by these people in secret it is disgraceful even to speak of.
Ephesians 5:15
Therefore be very careful how you live and act. Let it not be as unwise men, but as wise.
Hebrews 12:15
Be carefully on your guard lest there be any one who falls back from the grace of God; lest any root bearing bitter fruit spring up and cause trouble among you, and through it the whole brotherhood be defiled;