John Gill Commentary Hebrews 3:15

"while it is said, To-day if ye shall hear his voice, Harden not your hearts, as in the provocation." — Hebrews 3:15 (ASV)

While it is said today Exhort one another, and hold fast Christ and his Gospel, and faith and confidence therein; what follows is a repetition of the citation in (Hebrews 3:7Hebrews 3:8) in order to make a further improvement of it; which shows, that the words belong to the present times of the Gospel, and contain in them matter of moment, and great concern; and that Scripture instructions and exhortations are of perpetual use.