Hebrews 4:5-7

5and in this again, If they shall enter into my rest.

6Seeing therefore it remains that some enter into it, and those who first received the glad tidings did not enter in on account of not hearkening to the word,

7again he determines a certain day, saying, in David, 'To-day,' after so long a time; (according as it has been said before), To-day, if ye will hear his voice, harden not your hearts.