Charles Ellicott Commentary 2 Kings 16:18

"And the covered way for the sabbath that they had built in the house, and the king`s entry without, turned he unto the house of Jehovah, because of the king of Assyria." — 2 Kings 16:18 (ASV)

The covert for the sabbath. —A very obscure expression. The best interpretation is “the covered hall (or stand) set apart for the use of the king and his attendants when he visited the Temple on holy days” (reading, with the Hebrew margin, mûsak, which is attested by the Vulgate, musach, and the Syriac “house of the sabbath”). The thing is not mentioned anywhere else.

In the house — i.e., in the sacred precincts, probably in the inner forecourt.

The king’s entry without. — The outer entry of the king, i.e., the gate by which the king entered the inner court (Ezekiel 46:1–2).

Turned he from the house of the Lord.—Or, he altered in the house of the Lord, i.e., stripped them of their ornamental work.

For. —Or, from fear of ...—But compare Genesis 6:13, through them. Ahaz dared not appear before Tiglath without a present. It is possible also that he anticipated a visit from the great king.