Hebrews does say that.
you must read all of the book not just part of it.
chapter three says :
7 So, as the Holy Spirit says:
“Today, if you hear his voice,
8 do not harden your hearts
as you did in the rebellion,
during the time of testing in the wilderness,
9 where your ancestors tested and tried me,
though for forty years they saw what I did.
10 That is why I was angry with that generation;
I said, ‘Their hearts are always going astray,
and they have not known my ways.’
11 So I declared on oath in my anger,
‘They shall never enter my rest.’ ”
The above is speaking about the children of Isreal who did not believe but committed idolatry.
The writer goes on to say :
12 See to it, brothers and sisters, that none of you has a sinful, unbelieving heart that turns away from the living God.
This saying doesn't be like the above I just told you about.
Unbelief is the cause of all that is being said in Chapter 3.
19 So we see that they were not able to enter, because of their unbelief.
Chapter four :
12 For the word of God is alive and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart. 13 Nothing in all creation is hidden from God’s sight. Everything is uncovered and laid bare before the eyes of him to whom we must give account.
Jesus the Great High Priest
14 Therefore, since we have a great high priest who has ascended into heaven, Jesus the Son of God, let us hold firmly to the faith we profess. 15 For we do not have a high priest who is unable to empathize with our weaknesses, but we have one who has been tempted in every way, just as we are—yet he did not sin. 16 Let us then approach God’s throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need.
chapter five :
7 During the days of Jesus’ life on earth, he offered up prayers and petitions with fervent cries and tears to the one who could save him from death, and he was heard because of his reverent submission. 8 Son though he was, he learned obedience from what he suffered 9 and, once made perfect, he became the source of eternal salvation for all who obey him 10 and was designated by God to be high priest in the order of Melchizedek.
Warning Against Falling Away
11 We have much to say about this, but it is hard to make it clear to you because you no longer try to understand. 12 In fact, though by this time you ought to be teachers, you need someone to teach you the elementary truths of God’s word all over again. You need milk, not solid food! 13 Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. 14 But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil.
this is speaking of the immature believer who is not fully developed. Still growing and we all remain in the sanctification process but are accountable for our action in the flesh.
chapter 6:
Therefore let us move beyond the elementary teachings about Christ and be taken forward to maturity,
not laying again the foundation of repentance from acts that lead to death, and of faith in God,
2 instruction about cleansing rites, the laying on of hands, the resurrection of the dead, and eternal judgment. 3 And God permitting, we will do so.
4 It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, 5 who have tasted the goodness of the word of God and the powers of the coming age
6 and who have fallen away, to be brought back to repentance. To their loss, they are crucifying the Son of God all over again and subjecting him to public disgrace.
Chapter six goes on to say:
9 Even though we speak like this, dear friends, we are convinced of better things in your case—the things that have to do with salvation.
10 God is not unjust; he will not forget your work and the love you have shown him as you have helped his people and continue to help them.
11 We want each of you to show this same diligence to the very end, so that what you hope for may be fully realized. 12 We do not want you to become lazy, but to imitate those who through faith and patience inherit what has been promised.
chapter 10
A Call to Persevere in Faith
19 Therefore, brothers and sisters, since we have the confidence to enter the Most Holy Place by the blood of Jesus, 20 by a new and living way opened for us through the curtain, that is, his body, 21 and since we have a great priest over the house of God, 22 let us draw near to God with a sincere heart and with the full assurance that faith brings, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. 23 Let us hold unswervingly to the hope we profess, for he who promised is faithful. 24 And let us consider how we may spur one another on toward love and good deeds, 25 not giving up meeting together, as some are in the habit of doing, but encouraging one another—and all the more as you see the Day approaching.
only to those who give up and remain unrepentant are not restored.
