9. therefore--because God "speaks of another day" (see on Heb 4:8).
      remaineth--still to be realized hereafter by the "some (who) must enter therein" (Heb 4:6), that is, "the people of God," the true Israel who shall enter into God's rest ("My rest," Heb 4:3). God's rest was a Sabbatism; so also will ours be.
      a rest--Greek, "Sabbatism." In time there are many Sabbaths, but then there shall be the enjoyment and keeping of a Sabbath-rest: one perfect and eternal. The "rest" in Heb 4:8 is Greek, "catapausis;" Hebrew, "Noah"; rest from weariness, as the ark rested on Ararat after its tossings to and fro; and as Israel, under Joshua, enjoyed at last rest from war in Canaan. But the "rest" in this Heb 4:9 is the nobler and more exalted (Hebrew) "Sabbath" rest; literally, "cessation": rest from work when finished (Heb 4:4), as God rested (Re 16:17). The two ideas of "rest" combined, give the perfect view of the heavenly Sabbath. Rest from weariness, sorrow, and sin; and rest in the completion of God's new creation (Re 21:5). The whole renovated creation shall share in it; nothing will there be to break the Sabbath of eternity; and the Triune God shall rejoice in the work of His hands (Zep 3:17). Moses, the representative of the law, could not lead Israel into Canaan: the law leads us to Christ, and there its office ceases, as that of Moses on the borders of Canaan: it is Jesus, the antitype of Joshua, who leads us into the heavenly rest. This verse indirectly establishes the obligation of the Sabbath still; for the type continues until the antitype supersedes it: so legal sacrifices continued till the great antitypical Sacrifice superseded it, As then the antitypical heavenly Sabbath-rest will not be till Christ, our Gospel Joshua, comes, to usher us into it, the typical earthly Sabbath must continue till then. The Jews call the future rest "the day which is all Sabbath."

JFB.