In the book of Hebrews, the author shifts back and forth constantly between expositional sections and exhortational sections. It is a very difficult book to outline party because the text is constantly "on the move." Nevertheless, Hebrews 10:19 begins an exhortational (=hortatory) section where the author calls his hearers to action. He begs them to draw near, hold fast, and stimulate others toward good deeds in the Church (10:19-25). Then the author includes arguably the sternest warning in all the book of Hebrews where he tells them that if they continue sinning deliberately there is nothing that awaits them but a terrifying expectation of God's judgment (just look at the context of the OT quotations of Heb 10:30 — Deut 32:35, 36). Chapter 10:32 begins a new section where the author calls them to endurance in the midst of hardship (10:36). They have endured sufferings (10:32). They have undergone public reproaches and great persecution (10:32-34). And in so far as they have suffered, they are still called to "endure" so that they will receive "the promise" (10:36).
Then to substantiate his argument, the author of Hebrews provides two OT quotations — Isaiah 26:20 and Habakkuk 2:3-4.
Isaiah 26 is a song of trust in Yahweh's protection of his people. Yet the larger context includes the people of God who are suffering. In fact, Isa 26:17ff refers to the people of Israel as a pregnant woman approaching the time of her birth with pain, agony, and eager expectation. The quote is in v.20 where God tells them to "hide and wait a little while until indignation runs its course." Then, v.21 reveals that Yahweh will come out from His place to punish wicked ones for their iniquities.
Similarly, Habakkuk's context reveals the heart-wrenching confusion of Habakkuk. Why does God allow those more wicked to destroy His people? How does he seem inactive? Why does he seem to be apathetic? God responds to Habakkuk's complaints beginning in 2:2. Yahweh said that the vision that he is to write down (2:2) is yet for the "appointed time" and it will hasten toward the goal and it will not fail. Though it tarries, wait for it. This means that the deliverance Habakkuk longed for will come — in its proper time. But that's God's business — His timing is always perfect. Habakkuk's responsibility consists of not being "proud" (I keep the Masoretic Text [MT] as is without emendation) but rather being a righteous one who "lives by his faith" (2:4). Yes, deliverance from hardship will come. It will most certainly come. But Habakkuk's job is to wait and be patient. He is called to endure and live by faith.
This fits most perfectly in the immediate context of Hebrews 10 and the argument that the author impresses on his hearers. In the midst of severe persecution and dark oppression, they are called to endure by faith and wait for the deliverance of the LORD.
Here is part of the conclusion of my paper:
The believers to whom the author of Hebrews wrote struggled to endure, but if they will endure they shall receive the promise of God (10:35–36). Therefore, to reinforce this point in a hortatory challenge, the author combines two texts from the OT to prove his case as he sets their situation against the backdrop of the Parousia of Jesus Christ (10:37–38). Just as the people in both Isaiah and Habakkuk’s day were to endure hardship and persecution knowing that God would bring deliverance in the future, so also the readers of the epistle of Hebrews are called to endure hardship and persecution knowing that God will come (ὁ ἐρχόμενος) and bring deliverance. But until that time comes they must live by faith (ἐκ πίστεως). Thus, the writer states that the righteous one lives by faith but yet the one who shrinks back and refuses to endure finds no pleasure with God.