Hebrews 2:2

2:2 For if the message spoken through angels ¹  proved to be so firm that every violation ²  or disobedience received its just penalty,

Hebrews 5:8

5:8 Although he was a son, he learned obedience through the things he suffered. ³ 

Hebrews 10:23

10:23 And let us hold unwaveringly to the hope that we confess, for the one who made the promise is trustworthy.

¹ sn The message spoken through angels refers to the OT law, which according to Jewish tradition was mediated to Moses through angels (cf. Deut 33:2; Ps 68:17-18; Acts 7:38, 53; Gal 3:19; and Jub. 1:27, 29; Josephus, Ant. 15.5.3 [15.136]).

² tn Grk “through angels became valid and every violation.”

³ sn There is a wordplay in the Greek text between the verbs “learned” (ἔμαθεν, emaqen) and “suffered” (ἔπαθεν, epaqen).