"Today, if you hear his voice, do not harden your hearts

Hebrews chapter 2 and 3.

"We must pay more careful attention, therefore, to what we have heard, so that we do not drift away." vs. 2: 1
"Fix your thoughts on Jesus" 3:1

3:12 See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God. But encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin's deceitfulness. We have come to share in Christ if we hold firmly till the end the confidence we had at first. As has just been said:

"So, as the Holy Spirit says: "Today, if you hear his voice, do not harden your hearts.... Today if you hear his voice, do not harden your hearts as you did in the rebellion.