NIV 1984 Bible (PDF)

12See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God.

13But encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin's deceitfulness.

14We have come to share in Christ if we hold firmly till the end the confidence we had at first.

15As has just been said: "Today, if you hear his voice, do not harden your hearts as you did in the rebellion."