Let us therefore fear, lest, a promise being left us of entering into his rest, any of you should seem to come short of it.
Let us therefore fear - not with slavish terror, but godly "fear and trembling" (Philippians 2:12). Since so many have fallen, we have cause to fear (Hebrews 3:17-19).
Being left us - still remaining to us after the others have, by neglect, lost it. Or, though the earthly rest has been entered, the promise of the heavenly still remains.
His rest - God's heavenly rest, of which Canaan is the type. "Today" continues, during which is the danger of failing to reach the rest. "Today," rightly used, terminates in the rest which, when once obtained, is never lost (Revelation 3:12). A foretaste of the rest is given in the inward rest which the believer's soul has in Christ (Matthew 11:28-29).
Should seem to come short of it, х hustereekenai (G5302)] - 'to be come too late, when the "today" is gone (Hebrews 12:15; Luke 13:25): 'to have come short of it.' The word "seem" mitigates the expression, though not lessening the reality (Bengel). Lest there should be any semblance of falling short.