faithful

Hebrews 3
12 Be careful then, dear brothers and sisters.

           Make sure that your own hearts are not evil and unbelieving, turning you away from the living God.

13 You must warn each other every day, while it is still "today," so that none of you will be deceived by sin and hardened against God.

14 For if we are faithful to the end, trusting God just as firmly as when we first believed, we will share in all that belongs to Christ.

15 Remember what it says:

"Today when you hear his voice,
  don't harden your hearts
  as Israel did when they rebelled."