So God's rest is there for people to enter. But those who formerly heard the Good News failed to enter because they disobeyed God.
So God set another time for entering his place of rest, and that time is today. God announced this through David a long time later in the words already quoted: "Today you must listen to his voice. Don't harden your hearts against him."
References for Hebrews 4:7
This new place of rest was not the land of Canaan, where Joshua led them. If it had been, God would not have spoken later about another day of rest.