7 Therefore, as the Holy Spirit says,

  “Today, if you hear his voice,
8   do not harden your hearts as in the rebellion,
    on the day of testing in the wilderness,
9   where your fathers put me to the test
    and saw my works for forty years.
10   Therefore I was provoked with that generation,
  and said, ‘They always go astray in their heart;
    they have not known my ways.’
11   As I swore in my wrath,
    ‘They shall not enter my rest.’”

12 Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. 13 But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin. 14 For we have come to share in Christ, if indeed we hold our original confidence firm to the end. 15 As it is said,

  “Today, if you hear his voice,
  do not harden your hearts as in the rebellion.”

16 For who were those who heard and yet rebelled? Was it not all those who left Egypt led by Moses? 17 And with whom was he provoked for forty years? Was it not with those who sinned, whose bodies fell in the wilderness? 18 And to whom did he swear that they would not enter his rest, but to those who were disobedient? 19 So we see that they were unable to enter because of unbelief.

— Hebrews 3:7-19