^a Gk. πάλαι (see En. paleo-) refers to the indefinite past; usually implying long ago but can be the recent past (e.g., Mk. 15:44).

^b Gk. πολυμερῶς, lit. many-partly, i.e., piecemeal or part-by-part. The author of Hebrews is about to start drawing together these various parts in 1:3.

^c Gk. πολυτρόπως, in or by many manners. Τρόπος is a manner, way, or approach to doing something.
Possibly this refers to the diverse types of messianic scripture—both direct and indirect—from which the author is about to start quoting: promises to David about Solomon (in 2 Sm. and 1 Chr.); the Song of Moses (Dt. 32); psalms of praise to God (Ps. 104); royal wedding psalms (Ps. 45); psalms of prayer to God (Ps. 102); and coronation psalms (Ps. 110).
Since this letter is addressing Jews, familiarity with the quoted scriptures, their original contexts within full scripture, and their historically accepted and taught messianic application is presumably assumed.

^a God is finally speaking through the long-awaited Messiah prophesied in Ps. 2:7-8, and referenced in Heb. 1:5: The king says,I will announce the Lord’s decree. He said to me: / You are my son! This very day I have become your father! / Ask me, / and I will give you the nations as your inheritance, / the ends of the earth as your personal property (NET).

^b Gk. ἐποίησεν τοὺς αἰῶνας (see also Col 1:16: ἐν αὐτῷ ἐκτίσθη τὰ πάντα [in him all things were created]). Possibly reconciling the age of the patriarchs (Enoch, Noah, and Abraham) with the current age? (Heb. 11:13a: "These all died in faith without receiving the things promised..." and Heb. 11:40: "For God had provided something better for us, so that they [the patriarchs] would be made perfect together with us....")

^a Gk. ἀπαύγασμα. Cf. Wsd. 7:26: ἀπαύγασμα γάρ ἐστιν φωτὸς ἀϊδίου καὶ ἔσοπτρον ἀκηλίδωτον τῆς τοῦ θεοῦ ἐνεργείας καὶ εἰκὼν τῆς ἀγαθότητος αὐτοῦ [For she [wisdom] is the brightness of the everlasting light, the unspotted mirror of the power of God, and the image of his goodness (Brenton)].

^b Gk. χαρακτήρ, etching or engraving (see En. character); in Lv 13:28 it is the scar from a burn. The son is a visual impression or evidence or telltale sign of the otherwise unseen. (See also Col. 1:15: εἰκὼν τοῦ θεοῦ τοῦ ἀοράτου [an image of the invisible God].)

^c Gk. ὑπόστασις (see En. hypostasis).

^d Maybe an allusion to Ps. 145(:4,6,7,11,21)? (Is Ps. 145 referenced elsewhere in Hebrews?)

^e Allusion to Ps. 110:1, referenced in Heb. 1:13: Here is the Lord’s proclamation to my lord: / Sit down at my right hand until I make your enemies your footstool! (NET).

^f Gk. καθίζω. Perhaps an allusion to Dt 32:43, referenced in Heb. 1:6: Rejoice, ye heavens, with him, and let all the angels of God worship him; rejoice ye Gentiles, with his people, and let all the sons of God strengthen themselves in him; for he will avenge the blood of his sons, and he will render vengeance, and recompense justice to his enemies, and will reward them that hate him; and the Lord shall purge [ἐκκαθαριεῖ, purify] the land of his people (Benton). (See also Col 1:14: ἐν ᾧ ἔχομεν τὴν ἀπολύτρωσιν, τὴν ἄφεσιν τῶν ἁμαρτιῶν [in whom we have redemption, the forgiveness of sins].)

^a Hebrews is building up to a warning against the penalty of ignoring Jesus, demonstrating that his authority as the Messiah is greater than the angels (Heb. 1:5-13), whose spoken word is inviolable (Heb. 2:2), and greater than Moses, who the ancient Israelites refused to trust (Heb. 3:2-19).

^b See heir in 1:2. He inherited the name son when he was named heir.

^a God's angels propel God's servants [λειτουργούς] in the same way that wind fuels a fire.

^a "You Lord" addresses God. Psalm 101(102) is a penitential psalm addressed to God that states that the earth and the heavens will perish, in contrast to Psalm 44(45) which promises a Davidic throne that will last forever and ever. The throne God promised to David, therefore, is not an earthly throne but transcends into the spiritual realm. Jesus himself, when he challenged the Pharisees by asking them whose son the Christ will be (Mt. 22:41-46), alluded to the fact that the Messiah would not simply be an earthly ruler like David and Solomon. Any assumption that the angels are inherently superior because they are heavenly beings is undermined by this.

^a Gk. λειτουργικός, of or relating to public service or office. Like the Levites, who were charged with the duties of the tabernacle on behalf of all the Israelites—their liturgy, lit. public work—so, too, the angels are spirits charged with a specific office or function to perform. BDAG: spirits in special service to (God).