Hebrews 10:38-39
38 Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him.
39 But we are not of them who draw back unto perdition; but of them that believe to the saving of the soul.
The Grace New Testament Commentary - Hebrews 10:37-39
10:37-39 The time of such reward is at the return of Jesus. Quoting from the LXX translation of Hab 2:3-4, the author reminds them that "He who is coming will come and will not tarry" (cf. Heb 9:28). The Lord's return should mean good news for believers, but for some it could mean shame (cf. 1 John 2:28). Consequently he reminds them that "the just" are to "live by faith" - an enduring faith that he will illustrate in chap. 11 - and not draw back, that is, to turn cowardly from the Lord (by abandoning one's confession). The "just" one (dikaios; lit., "righteous one") can potentially do either, but by "drawing back" the Lord will take "no pleasure in him," that is, He will not be pleased with such an unfaithful believer.
The chapter ends, "We, however, are not of those who cowardly turn back resulting in destruction, but we are of those who exhibit an enduring faith resulting in the preservation of the soul" (my translation). The NKJV translation perdition (apōleian) in v 39 might better be rendered "destruction." This term can be used of people (including believers) in cases where eternal damnation is not in view (such as 1 Tim 6:9 and Acts 8:20). Also the related verb form (apōllumi) can refer to temporal physical destruction (e.g., Mark 4:38). Most likely the author is thinking once again of the stern judgment that he had spoken of in Heb 10:29.
Since he had just spoken of the fate of the believer when the Lord returns, this could mean not only temporal destruction but a negative experience at the judgment seat of Christ (coming short of God's rest; Hebrews 4:1). Any thought, however, that Hebrews 10:39 might have soteriological faith in view must certainly be rejected in light of the fact that the author clearly portrays in chapter 11 that the faith he has in mind is a life of walking by faith in which one pleases God.