Though this Chapter which should be included in Chapter 3, is about resting in Christ, I believe is also about Heaven.
"Let us therefore fear, lest, a promise being left us of entering into his rest, any of you should seem to come short of it."-Hebrews 4:1
"There remaineth therefore a rest to the people of God."-Hebrew 4:9
Matthew Henry says,
"Let us then give diligence, that we may have a clear entrance into the kingdom of God."
And also says.
"The rest, or sabbatism, which is the subject of the apostle's reasoning, and as to which he concludes that it remains to be enjoyed, is undoubtedly the heavenly rest, which remains to the people of God, and is opposed to a state of labour and trouble in this world. It is the rest they shall obtain when the Lord Jesus shall appear from heaven. But those who do not believe, shall never enter into this spiritual rest, either of grace here or glory hereafter."