'Be Careful' in the Bible

Therefore be careful that the light in you is not darkness.

According to the grace of God which was given to me, like a wise master builder I laid a foundation, and another is building on it. But each man must be careful how he builds on it.

Be careful, then, how you walk, not as unwise men, but as wise,

This is a trustworthy saying; and concerning these things I want you to speak confidently, so that those who have believed God may be careful to devote themselves to good deeds. These things are excellent and profitable for men.