A.T. Robertson Commentary Hebrews 9:25

"nor yet that he should offer himself often, as the high priest entereth into the holy place year by year with blood not his own;" — Hebrews 9:25 (ASV)

That he should offer himself often (ινα πολλακις προσφερη εαυτον). Purpose clause with ινα and present active subjunctive of προσφερω (keep on offering himself, like 5:1,3).

With blood not his own (εν αιματ αλλοτριω). So-called instrumental use of εν (accompaniment). αλλοτριος means "belonging to another," "not one's own" (Luke 16:12).