Hebrews 2:3
how shall we escape, having neglected so great salvation; which, indeed, having at first been spoken through the Lord, was confirmed to us by those who heard;
Hebrews 6:6
and then fell away, it is impossible to renew them again to repentance, since they are crucifying to themselves the Son of God afresh, and putting Him to open shame.
Hebrews 9:28
so also Christ, having once for all been offered to bear the sins of many, will, to those who are eagerly waiting for Him; appear a second time apart from sin, unto salvation.
Hebrews 10:26-29
For, if we sin wilfully after we received the full knowledge of the truth, there no longer remains a sacrifice for sins,
Hebrews 12:25
See that ye refuse not Him Who speaketh; for, if those escaped not, when refusing him who warned them on earth, much more shall not we escape, who turn away from Him Who warneth us from Heaven;