It needs to be most carefully observed that in this verse the Holy Spirit employs an entirely different word for “rest” than what he had used in vv. 1, 3, 4, 5 and 8. There the Greek word is rightly rendered “rest,” but here it is “sabbatismos” and its meaning has been properly given by the translators in the margin—“keeping of a Sabbath.”
via A.W. Pink’s Exposition of Hebrews 4:9-10 [sabbatismos] | The Confessing Baptist.