Surah 34. Saba, Ayah 13

I.e., because of their enormous size. Cf. II Chronicles iii, 10-13, where statues ("images") of cherubim are mentioned, as well as iv, 2-5, describing "a molten sea" (i.e., basin) of huge dimensions, resting upon twelve statues of oxen, and meant to contain water "for the priests to wash in" (ibid., iv, 6). The "sanctuaries" were apparently the various halls of the new temple.

These words, ostensibly addressed to "the people" or "the family" of David, are in reality an admonition to all believers, at all times, since all of them are, spiritually, "David's people".

I.e., even among those who consider themselves God's servants - for "truly grateful [to God] is only he who realizes his inability to render adequate thanks to Him" (Zamakhshari).

 Which was permissible at the time of Solomon (ﷺ).

Mihrab (Plural Maharib), translated "arch", may be applied to any fine, elevated, spacious architectural structure. As the reference here is to the Temple of Solomon, the word "arches" is I think most appropriate. "Arches" would be structural Ornaments in the Temple. Images would be like the images of oxen and Cherubim mentioned in II. Chronicles, iv. 3 and iii. 14; the Basons (11. Chronicles iv. 22) were perhaps huge dishes round which many men could sit together and eat, according to ancient Eastern custom, while the cooking Cauldrons or Pots (II. Chronicles, iv. 16), were fixed in one place, being so large in capacity that they could not be moved about. Indian readers will get some idea of them from the huge cooking Degs, which they use in the festivals.

The building of the Temple was a great event in Israelite history. They are asked to be thankful without which all that glory and power would be out of place, and it fell away in a few generations, with the decline of the moral spirit which was at its back.