A. Therefore: The idea is carried on without pause from Hebrews 3, that unbelief kept the generation that escaped Egypt from entering Canaan. The promise remains of entering His rest, and we can enter into that rest by faith. Unbelief will make us fall short of the rest God has for us.
The old Puritan commentator John Owen described five features of this rest for the believer:
B. Let us fear lest any of you seem to have come short of it: This place of rest is so wonderful it should concern us when others or we seem to come short of it. It isn’t enough to almost enter His rest; we don’t want to come short of it.
Based on the Enduring Word Bible Commentary by David Guzik.