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 6:9

6:9 But in your case, dear friends, even though we speak like this, we are convinced of better things relating to salvation.

Hebrews 7:8

7:8 and in one case tithes are received by mortal men, while in the other by him who is affirmed to be alive.