Hebrews 4:7

God again designated a certain day as “Today,” when a long time later He spoke through David as was just stated: “Today, if you hear His voice, do not harden your hearts.”

Note Psalms 95:7–8

BSB · Berean Standard Bible
Again, he limiteth a certain day, saying in David, To day, after so long a time; as it is said, To day if ye will hear his voice, harden not your hearts.
KJV · King James Version
he again defines a certain day, “today”, saying through David so long a time afterward (just as has been said), “Today if you will hear his voice, don’t harden your hearts.”
WEB · World English Bible
he again defineth a certain day, To-day, saying in David so long a time afterward (even as hath been said before), To-day if ye shall hear his voice, Harden not your hearts.
ASV · American Standard Version

Related passages

From the Treasury of Scripture Knowledge, grouped by the word they explain.

saying
Hebrews 3:7, 8; 2 Samuel 23:1, 2; Matthew 22:43; Mark 12:36; Luke 20:42; Acts 2:29, 31; Acts 28:25
To day
Hebrews 3:7, 15; Psalm 95:7
after
1 Kings 6:1; Acts 13:20–23