Charles Ellicott Commentary 2 Chronicles 6:14

"and he said, O Jehovah, the God of Israel, there is no God like thee, in heaven, or on earth; who keepest covenant and lovingkindness with thy servants, that walk before thee with all their heart;" — 2 Chronicles 6:14 (ASV)

In the heaven nor in the earth. —Abridged from in the heaven above, and upon the earth beneath (the Book of Kings). Syriac, “You are the Lord that sit in heaven above, and Your will (plural) is done on earth beneath;” apparently a curious reminiscence of the Lord’s Prayer. The Assyrians also spoke of their gods as “without an equal” (sânina la isû, “a rival he has not”).

Which keep covenant and show mercy. —Literally, keeping the covenant and the mercy; i.e., the covenanted mercy. (Compare Isaiah 55:3.)

With your servant. —Hebrew, for; so in 2 Chronicles 6:16. (The verse is word for word as in the Book of Kings.)

And spoke with your mouth... — 2 Chronicles 6:4.