John Lightfoot on Matthew 27:51

[The veil of the Temple was rent in twain, &c.] Let us hear what the Fathers of the Traditions say concerning this catapetasm or veil: "The wall of the pronaon was five cubits, the pronaon itself eleven. The wall of the Temple was six, the Temple forty. The taraxis one cubit, and the entrance, twenty." What taraxis means, Maimonides will tell you; "In the first Temple there was a wall one cubit thick, separating the Holy from the Holy of Holies; but when they built the second Temple, it was doubted whether the thickness of that wall should be accounted to belong to the measure of the Holy, or to the measure of the Holy of Holies. Wherefore they made the Holy of Holies twenty cubits complete, and the Holy forty cubits complete; and they left a void cubit between the Holy and the Holy of Holies, but they did not build any wall there in the second Temple: only they made two hangings, one contiguous to the Holy of Holies, and the other to the Holy; between which there was a void cubit, according to the thickness of the wall that was in the first Temple; in which there was but one catapetasm [or veil] only."

"The high priest [on the day of atonement] goes forward in the Temple, till he comes to the two hangings that divide the Holy from the Holy of Holies, between which there was a cubit. R. Josi saith, There was but one hanging there; as it is said, 'And the hanging shall separate [to, or] between the Holy and the Holy of Holies.'" On which words thus the Gemara of Babylon: "R. Josi saith rightly to the Rabbins, and the Rabbins to thee: for he speaks of the tabernacle, and they, of the second Temple; in which since there was not a partition-wall, as there was in the first Temple, there was some doubt made of its holiness, namely, whether it should belong to the outward part of the Temple or to the inward; whereupon they made two hangings."

While, therefore, their minds were troubled about this affair, not knowing whether they should hang the veil at the Temple, or at the inmost recess of it, and whether the void space between of a cubit thick should belong to this or that; they called the place itself by the Greek word taraxis, that is, trouble, as Aruch plainly affirms, and they hung up two veils, that they might be sure to offend neither against this part nor that.

You will wonder, therefore, that Matthew doth not say veils, in the plural; or perhaps you will think that only one of these two veils was rent, not both. But it was enough for the evangelists Matthew and Mark, who speak of this miracle, to have shewed that that fence between, which hindered seeing into the Holy of Holies, and going into it, was cleft and broken. This is it they mean, not being solicitous in explaining particulars, but contented to have declared the thing itself. Perhaps the priest, who offered the incense that evening, was in the Temple at the very moment when this miracle happened: and when he went out amazed to the people, and should tell them, The veil of the Temple is rent it would easily be understood of a passage broken into the Holy of Holies by some astonishing and miraculous rending of the hangings. Compare Hebrews 10:19,20.

When the high priest went into the inmost recess of the Temple on the day of atonement, he went in by the south side of the outward hanging, and the north side of the inner. But now both are rent in the very middle, and that from the top to the bottom.