Albert Barnes Commentary 2 Samuel 7:15

"but my lovingkindness shall not depart from him, as I took it from Saul, whom I put away before thee." — 2 Samuel 7:15 (ASV)

My mercy shall not depart ... - This is why Isaiah speaks of the sure mercies of David (Isaiah 55:3)—that is, unfailing, lasting mercies, like streams of water that never dry up (Isaiah 33:16; Jeremiah 15:18). This is explained in 2 Samuel 7:16, where the word "established" is the same word rendered as "sure" in Isaiah.

Before you - The reading Before Me is likely the correct one in 2 Samuel 7:15–16 (if the rest of the text is sound), based on the analogy of Jeremiah 35:19, 1 Samuel 2:30, 1 Samuel 2:35, and many other passages. In contrast, the idea contained in the reading before you is unparalleled. However, the reading in 1 Chronicles 17:13 is quite different: As I took it from him that was before you. This refers to Saul, provides a very good sense, and suggests that the text here may have been corrupted.