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 6:18

6:18 so that we who have found refuge in him ¹  may find strong encouragement to hold fast to the hope set before us through two unchangeable things, since it is impossible for God to lie.

[6:18]  ¹ tn Grk “have taken refuge”; the basis of that refuge is implied in the preceding verse.