God's REST was introduced in Chapter 3:11 & 18; that emphasis continues in Chapter 4. In Hebrews 4, the writer uses the word REST to refer to three different things.
God's work of creation, Hebrews 4:4, 10; Entrance into the Promised Land; A place of spiritual rest, vs. 8-11.
We need to understand that we can't earn this REST. We don't work our way in; we faith our way in. So, how do we enter the place of God's REST?
It involves daily surrender, v. 3; It involves submitting to the Word of God, v. 12; It involves trusting only in the mercy of God, v.16.
Hebrews 4 closes with some of the most precious words in all of Scripture, vs. 15-16. This summarizes living in the place of God's REST. We enter by faith, through a yielded heart. We remain, by the power of God's grace, through His never-ending mercy.