Albert Barnes Commentary Hebrews 5:3

"and by reason thereof is bound, as for the people, so also for himself, to offer for sins." — Hebrews 5:3 (ASV)

And by reason hereof. On this account: because he is a sinner—an imperfect man.

As for the people, so also for himself, to offer for sins. To make an expiation for sins. He needs the same atonement; he offers the sacrifice for himself which he does for others (Leviticus 9:7).

The same thing is true of ministers of religion now. They come before God feeling that they need the benefit of the same atonement which they preach to others; they plead the merits of the same blood for their own salvation, which they show to be indispensable for the salvation of others.