Hebrews 2:13

I will put my trust in him--from the Septuagint, Isa 8:17, which immediately precedes the next quotation, "Behold, I and the children," &c. The only objection is the following words, "and again," usually introduce a new quotation, whereas these two are parts of one and the same passage. However, this objection is not valid, as the two clauses express distinct ideas; "I will put my trust in Him" expresses His filial confidence in God as His Father, to whom He flees from His sufferings, and is not disappointed; which His believing brethren imitate, trusting solely in the Father through Christ, and not in their own merits. "Christ exhibited this "trust," not for Himself, for He and the Father are one, but for His own people" (Heb 2:16). Each fresh aid given Him assured Him, as it does them, of aid for the future, until the complete victory was obtained over death and hell Phi 1:16 [BENGEL]. Behold I and the children, &c.-- (Isa 8:18). "Sons" (Heb 2:10), "brethren" (Heb 2:12), and "children," imply His right and property in them from everlasting. He speaks of them as "children" of God, though not yet in being, yet considered as such in His purpose, and presents them before God the Father, who has given Him them, to be glorified with Himself. Isaiah (meaning "salvation of Jehovah") typically represented Messiah, who is at once Father and Son, Isaiah and Immanuel (Isa 9:6).

— Jamieson-Fausset-Brown Commentary (public domain)