And the pavement by the side of the gates over against the length of the gates was the lower pavement.

Wesley's Notes

40:18 The pavement - That mentioned, ver.17. By the side - That part which lay on each side of the gate, and from thence spread itself toward the chambers, leaving a space of pavement of equal breadth with the porch, or gate in the middle. The length - The length was measured fifty cubits. The inner pavement - The side pavement was laid somewhat lower than this middle pavement, not only for state, but for the more convenient, keeping it clean; so the middle pavement rose with a little convex surface.

Jamieson-Fausset-Brown Bible Commentary

18. The higher pavement was level with the entrance of the gates, the lower was on either side of the raised pavement thus formed. Whereas Solomon's temple had an outer court open to alterations and even idolatrous innovations (2Ki 23:11, 12; 1Ch 20:5), in this there was to be no room for human corruptions. Its compass was exactly defined, one hundred cubits; and the fine pavement implied it was to be trodden only by clean feet (compare Isa 35:8).

Matthew Henry's Concise Commentary

40:1-49 The Vision of the Temple. - Here is a vision, beginning at ch. 40, and continued to the end of the book, ch. 48, which is justly looked upon to be one of the most difficult portions in all the book of God. When we despair to be satisfied as to any difficulty we meet with, let us bless God that our salvation does not depend upon it, but that things necessary are plain enough; and let us wait till God shall reveal even this unto us. This chapter describes two outward courts of the temple. Whether the personage here mentioned was the Son of God, or a created angel, is not clear. But Christ is both our Altar and our Sacrifice, to whom we must look with faith in all approaches to God; and he is Salvation in the midst of the earth, Ps 74:12, to be looked unto from all quarters.