John Chrysostom

"And after the second veil" (There was then not one veil only, but there was a veil without also) "the tabernacle, which is called holy of holies." Observe how everywhere he calls it a tabernacle in regard of God's encamping there.

Homily on Hebrews 15 ↗

Theophylact of Ohrid

Do you see that there was a first veil, which Scripture calls a curtain, since it was rolled up and drawn together — this veil separated the court, into which everyone in general entered and upon which they offered sacrifices on the bronze altar, from the tabernacle, which was accessible to the priests who performed the daily services. …

Commentary on Hebrews ↗

Oecumenius

"And after the second veil." Therefore, there was not only one veil. A tabernacle is called everywhere, because there God dwells.

The Pseudo-Oecumenian Catena on Hebrews ↗

Thomas Aquinas

420. – Then when he says, Behind the veil the second tabernacle called the Holy of Holies, he describes the things that were in the second tabernacle, namely, the ark of the covenant made of incorruptible sethim wood, covered about on every part, i.e., inside and outside, with gold. In the ark were three things: a golden urn that had manna in memory of the benefit bestowed on them; the rod of Aaron that had blossomed (Num. …

Commentary on Hebrews ↗