Jamieson, Fausset and Brown on Hebrews 10:35-38

35-37. Consequent exhortation to confidence and endurance, as Christ is soon coming.

Cast not away--implying that they now have "confidence," and that it will not withdraw of itself, unless they "cast it away" wilfully (compare He 3:14).

which--Greek, "the which": inasmuch as being such as.

hath--present tense: it is as certain as if you had it in your hand (He 10:37). It hath in reversion.

recompense of reward--of grace not of debt: a reward of a kind which no mercenary self-seeker would seek: holiness will be its own reward; self-devoting unselfishness for Christ's sake will be its own rich recompense (see on He 2:2; He 11:26).