Charles Ellicott Commentary Hebrews 3:19

"And we see that they were not able to enter in because of unbelief." — Hebrews 3:19 (ASV)

So we see.—Rather, And we see. It is not the general conclusion that is expressed here; but, as in Hebrews 3:18 we read of the oath of exclusion, this verse records the fact, and also states the cause under an aspect most suitable for the exhortation in the writer’s thought. There is force in could not enter—not only disobedience, but cowardice and weakness, sprang from unbelief.