Hebrews 2:17

Wherefore--Greek, "Whence." Found in Paul's speech, Act 26:19. in all things--which are incidental to manhood, the being born, nourished, growing up, suffering. Sin is not, in the original constitution of man, a necessary attendant of manhood, so He had no sin. it behooved him--by moral necessity, considering what the justice and love of God required of Him as Mediator (compare Heb 5:3), the office which He had voluntarily undertaken in order to "help" man (Heb 2:16). his brethren-- (Heb 2:11); "the seed of Abraham" (Heb 2:16), and so also the spiritual seed, His elect out of all mankind. be, &c.--rather as Greek, "that He might become High Priest"; He was called so, when He was "made perfect by the things which He suffered" (Heb 2:10; Heb 5:8-10). He was actually made so, when He entered within the veil, from which last flows His ever continuing intercession as Priest for us. The death, as man, must first be, in order that the bringing in of the blood into the heavenly Holy Place might follow, in which consisted the expiation as High Priest. merciful--to "the people" deserving wrath by "sins.

— Jamieson-Fausset-Brown Commentary (public domain)