Hebrews 4:9

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 (Rev 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 (Rev 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).

— Jamieson-Fausset-Brown Commentary (public domain)