Hebrews 2:3
how shall we escape, if we neglect that salutary doctrine? which was first published by the Lord, and was confirmed to us by those that heard him;
Hebrews 6:6
if they shall fall away, to re-instate themselves by repentance: seeing, as far in them lies, they crucify the son of God afresh, and expose him to open shame.
Hebrews 9:28
so Christ being once offered up to take away the sins of many; he shall appear the second time, without making any further expiation to save those who expect him.
Hebrews 10:26-29
for if we wilfully apostatize, after having received the knowledge of the truth, it is as a sin for which there is no sacrifice appointed.
Hebrews 12:25
Take care that you be not deaf to him that speaketh: for if they did not escape, who disregarded the oracles pronounc'd on earth, much less shall we escape, if we turn away from him that delivered the oracles from heaven: