15 while it is said,

“Today if you will hear his voice,
don’t harden your hearts, as in the rebellion.” [1] 16 For who, when they heard, rebelled? No, didn’t all those who came out of Egypt by Moses? 17 With whom was he displeased forty years? Wasn’t it with those who sinned, whose bodies fell in the wilderness? 18 To whom did he swear that they wouldn’t enter into his rest, but to those who were disobedient? 19 We see that they were not able to enter in because of unbelief.

Matthew Henry's Commentary on Hebrews 3:15-19

Commentary on Hebrews 3:14-19

(Read Hebrews 3:14-19)

The saints' privilege is, they are made partakers of Christ, that is, of the Spirit, the nature, graces, righteousness, and life of Christ; they are interested in all Christ is, in all he has done, or will do. The same spirit with which Christians set out in the ways of God, they should maintain unto the end. Perseverance in faith is the best evidence of the sincerity of our faith. Hearing the word often is a means of salvation, yet, if not hearkened to, it will expose more to the Divine wrath. The happiness of being partakers of Christ and his complete salvation, and the fear of God's wrath and eternal misery, should stir us up to persevere in the life of obedient faith. Let us beware of trusting to outward privileges or professions, and pray to be numbered with the true believers who enter heaven, when all others fail because of unbelief. As our obedience follows according to the power of our faith, so our sins and want of care are according to the prevailing of unbelief in us.