The chapter opens by calling believers to consider Jesus as apostle and high priest of their confession.
Hebrews 3:1-6
1 Therefore, holy brothers, partakers of a heavenly calling, consider the Apostle and High Priest of our confession: Jesus,
Moses was faithful as a servant in God's house, but Jesus is faithful as the Son over God's house.
2 who was faithful to him who appointed him, as also Moses was in all his house.
3 For he has been counted worthy of more glory than Moses, because he who built the house has more honor than the house.
4 For every house is built by someone; but he who built all things is God.
5 Moses indeed was faithful in all his house as a servant, for a testimony of those things which were afterward to be spoken,
6 but Christ is faithful as a Son over his house. We are his house, if we hold fast our confidence and the glorying of our hope firm to the end.
Psalm 95 warns the hearers not to repeat Israel's wilderness rebellion.
Hebrews 3:7-19
7 Therefore, even as the Holy Spirit says, “Today if you will hear his voice,
8 don’t harden your hearts, as in the rebellion, like as in the day of the trial in the wilderness,
9 where your fathers tested me and tried me, and saw my deeds for forty years.
10 Therefore I was displeased with that generation, and said, ‘They always err in their heart, but they didn’t know my ways.’
11 As I swore in my wrath, ‘They will not enter into my rest.’ ”
The community must watch against unbelief and exhort one another daily before sin hardens the heart.
12 Beware, brothers, lest perhaps there might be in any one of you an evil heart of unbelief, in falling away from the living God;
13 but exhort one another day by day, so long as it is called “today”, lest any one of you be hardened by the deceitfulness of sin.
14 For we have become partakers of Christ, if we hold the beginning of our confidence firm to the end,
15 while it is said, “Today if you will hear his voice, don’t harden your hearts, as in the rebellion.”
The wilderness generation is remembered as a sober example of hearing God's voice yet failing to enter because of unbelief.
16 For who, when they heard, rebelled? Wasn’t it all those who came out of Egypt led by Moses?
17 With whom was he displeased forty years? Wasn’t it with those who sinned, whose bodies fell in the wilderness?
18 To whom did he swear that they wouldn’t enter into his rest, but to those who were disobedient?
19 We see that they weren’t able to enter in because of unbelief.