Albert Barnes on Hebrews 9:25

Nor yet that he should offer himself often. The Jewish high priest entered the most holy place with blood once every year. In this respect the offering made by Christ, and the work which he performed, differed from that of the Jewish high priest. It was not needful that he should enter the holy place but once. Having entered there, he permanently remains there.

With the blood of others. That is, with the blood of calves and goats. This is a second point in which the work of Christ differs from that of the Jewish high priest. Christ entered there with his own blood. Heb 9:12.