Then the LORD appeared to Solomon in the night and said to him: “I have heard your prayer and have chosen this place for myself as a house of sacrifice.
That God accepted Solomon's prayer appeared by the fire from heaven. But a prayer may be accepted and yet not answered in the letter of it; and therefore God appeared to him in the night, as he did once before (Ch2 1:7), and after a day of sacrifice too, as then, and gave him a peculiar answer to his prayer. We had the substance of it before, Kg1 9:2-9. I.
Commenting on 2 Chronicles 7:12-22
GOD APPEARS TO HIM. (Ch2 7:12-22) the Lord appeared to Solomon by night--(See on Kg1 9:1-9). The dedication of the temple must have been an occasion of intense national interest to Solomon and his subjects. Nor was the interest merely temporary or local. The record of it is read and thought of with an interest that is undiminished by the lapse of time.
The Lord appeared to Solomon - This was a second manifestation; see Kg1 9:2-9 (note), and the notes there. The Targum says, "The Word of the Lord appeared to Solomon."