Charles Ellicott Commentary 1 Kings 6:20

"And within the oracle was [a space of] twenty cubits in length, and twenty cubits in breadth, and twenty cubits in the height thereof; and he overlaid it with pure gold: and he covered the altar with cedar." — 1 Kings 6:20 (ASV)

In the forepart.—Although this is a literal translation of the original, the sense is clearly (as the Vulgate renders the phrase) “in the inner part.” Gesenius supposes the meaning to be properly, “the wall facing the entrance;” from there the opposite, or “inner,” wall or region.

Covered the altar ... —Our translators have been misled by the context to anticipate what is said below (1 Kings 6:22). The meaning is “he covered the altar” (presumably of stone) “with cedar.”