Hebrews 6:4

6:4 For it is impossible in the case of those who have once been enlightened, tasted the heavenly gift, become partakers of the Holy Spirit,

Hebrews 10:2

10:2 For otherwise would they not have ceased to be offered, since the worshipers would have been purified once for all and so have no further consciousness of sin?

Hebrews 12:26-27

12:26 Then his voice shook the earth, but now he has promised, “I will once more shake not only the earth but heaven too.” 12:27 Now this phrase “once more” indicates the removal of what is shaken, that is, of created things, so that what is unshaken may remain.