Hebrews 4:6
Seeing therefore it remaineth that some must enter there in, and they to whom it was first preached entered not in because of unbelief: Seeing therefore it remaineth that some must enter there in, and they to whom it was first preached entered not in because of unbelief:
Entry into God's rest still remains open, so that some must enter therein. Those to whom the message was first preached were Israel's first generation, who heard the promise but failed to enter because of unbelief and disbelief. God's rest in the verse denotes the promised land, and by extension the heavenly Canaan.
God intended to lead Israel directly and promptly to the promised land if they had submitted to Him and trusted His leading. But their repeated grieving of God prolonged the wilderness wandering until He swore they would not enter His rest, except for the two who wholly followed Him. Israel's history thus warns that people can miss that rest through persistent refusal to heed God's warnings and teachings. Israel's failure warns that people today are likewise in danger of failing to enter that rest through unbelief.
The verse warns God's people to trust in God alone rather than seek help from those who do not serve Him. The verse teaches that God's promise is fulfilled to those who obey and follow His leading. Having received light and privileges does not ensure entry, since those who fail to advance in holiness may retrogress even at the borders of heavenly Canaan.