For if Jesus had given them rest, then would he not afterward have spoken of another day.
Answer to the possible objection to his reasoning-namely, that those brought into Canaan by Joshua (so "Jesus," Acts 7:45) did enter the rest of God. If the rest of God meant Canaan, God would not, after their entrance into that land, have spoken of another (future) day of entering the rest.
Therefore - because God 'speaks of another day' (note, Hebrews 4:8).