1)
What is "ha'Ritzpah"?
1.
Radak: It is the floor of the Bayis. It is called Ritzpah because it is Merutzaf (tiled) with marble stone.
2)
Why does it say that they prostrated on the floor?
1.
Radak: It is because Shlomo prostrated on the Kiyor, on which he stood; they prostrated on the floor, where they stood.
2.
Malbim: One may not prostrate on a stone floor, except for in the Mikdash (Megilah 22b, Sifra). After they saw that this is the place that Hashem chose 1 , they bowed on the floor.
1
Had they not seen that Hashem chose it [via fire descending], would they not treat it like the Mikdash?! (PF)
