And since it was not without an oath he was made priest:
Read Chapter 7
George Leo Haydock
The old law was good in itself, being established by God, who does nothing in vain; but it was weak and imperfect, and the shadow and figure of that which was to come. It was preparatory to a more perfect dispensation under Jesus Christ, who, as our new high priest, was to finish by the gospel what Moses began by the law. ...
And forasmuch as not without the taking of an oath. You see that the matter of the oath becomes necessary for him here. Accordingly for this reason he previously treated much [hereon], how that God swore; and swore for the sake of [our] fuller assurance.
But the bringing in of a better hope. For that system also had a hope, but not such as this. For they hoped that, if they were well pleasing [to God], they should possess the land, that they should suffer nothing fearful. But in this [dispensation] we hope that, if we are well pleasing [to God], we shall possess not earth, but heaven; or rather (which is far better than this) we hope to stand near to God, to come unto the very throne of the Father, to minister unto Him with the Angels. And see how he introduces these things little by little. For above he says which enters into that within the veil, Hebrews 6:19, but here, by which we draw near unto God. ...