Albert Barnes Commentary 2 Samuel 12:13

"And David said unto Nathan, I have sinned against Jehovah. And Nathan said unto David, Jehovah also hath put away thy sin; thou shalt not die." — 2 Samuel 12:13 (ASV)

For a comment on David’s words, read Psalm 51 and Psalm 32:1-11.

You shall not die—This was not spoken of the punishment of death for adultery as prescribed by the Mosaic Law (Leviticus 20:10; Deuteronomy 22:22; John 8:5), because its application to an absolute Eastern monarch was out of the question. The death of the soul is meant (compare Ezekiel 18:4, 18:13, and 18:18).