John Gill Commentary 2 Chronicles 7:3

"And all the children of Israel looked on, when the fire came down, and the glory of Jehovah was upon the house; and they bowed themselves with their faces to the ground upon the pavement, and worshipped, and gave thanks unto Jehovah, [saying], For he is good; for his lovingkindness [endureth] for ever." — 2 Chronicles 7:3 (ASV)

And when all the children of Israel saw how the fire came down ,
&c.] From heaven upon the sacrifice, and consumed it, which was all visible to the eye; or it may be this was a distinct fire from the former, since it seems to have come down upon the house, and so may denote a bright, shining, glorious light; the same with what follows:

and the glory of the Lord upon the house ;
for not only the house was filled with the glory, but there was a bright stream of light and glory over it, very dazzling and surprising:

they bowed themselves with their faces to the ground upon the pavement ;
of the great court, where they were assembled:

and worshipped and praised the Lord :
worshipped him by praising him:

saying, for he is good ;
in his nature, promises, and blessings; is good, and does good:

for his mercy endureth for ever ;
this was the close of their song of praise.