John Chrysostom

Here we must apply our minds attentively, and consider the Apostolic wisdom; for again he shows the difference of the Priesthood. "Who" (he says) "serve unto the example and shadow of heavenly things." What are the heavenly things he speaks of here? The spiritual things. For although they are done on earth, yet nevertheless they are worthy of the Heavens. …

Homily on Hebrews 14 ↗

Theophylact of Ohrid

Here he shows the superiority of Christ's priesthood, calling the Old Testament priesthood "a copy and shadow," while ours is heavenly. For when nothing is earthly, but rather everything in the sacraments is spiritual, where there are angelic hymns, where there are the keys of the Kingdom of Heaven, and the forgiveness of sins, and again the binding; when our citizenship is in heaven, then how can our priesthood not be heavenly? …

Commentary on Hebrews ↗

Oecumenius

"who serve a copy and shadow of the heavenly things." Those who are priests of the Jews, he says. And how do they serve as a copy and shadow of the heavenly things? For he says, "See that you make everything according to the pattern that was shown to you on the mountain." And the things shown to him were heavenly. There were also services, and prayers, and sacrifices, and the construction of the tabernacle. …

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

388. – But according to the first explanation the reading is continued in the following way: There would be many who according to the law would offer such gifts, namely, those who serve a copy [exemplar] and shadow of heavenly things. The sacraments of the Old Law were figures of other things in two respects: first, in regard to knowledge; secondly, in regard to fulfillment. In regard to knowledge he says, exemplar, because in the Old Law, as in an exemplar could be read that to which our knowledge should be led. …

Commentary on Hebrews ↗