A lesson in NOT doing it your way.
Sabbath-rest is not a new thing. The writer of the book of Hebrews was using a well known example (to Jews) explaining life in Christ. The Sabbath, a day of rest from your labors, and a time to worship without the distractions of the ordinary necessities. Then, as now, rest was found in obeying God’s command of repentance, and trusting in His promise of salvation. No repentance, no assurance, no rest.
“This is what the Sovereign Lord, the Holy One of Israel, says: ‘In repentance and rest is your salvation, in quietness and trust is your strength, but you would have none of it.'” (Isaiah 30:15 NASB)
They did their own thing, relied upon themselves and practiced a pretend faith.
“The Lord says: ‘These people come near to me with their mouth and honor me with their lips, but their hearts are far from me. They worship me in vain; / their teachings are merely human rules.'” (Isaiah 29:13 NASB)
There is no substitute for the real thing: Repentance, resting in Jesus who is the Savior and worshiping God. It’s vain to pretend, We can not fool God, and nothing good comes from fooling others. Thinking that we can do our own thing without Jesus is to be without salvation. The problem? They did NOT believe. To not believe is disobedience.