Albert Barnes Commentary 1 Samuel 15:24

"And Saul said unto Samuel, I have sinned; for I have transgressed the commandment of Jehovah, and thy words, because I feared the people, and obeyed their voice." — 1 Samuel 15:24 (ASV)

I have sinned - Compare 1 Samuel 15:25, 1 Samuel 15:30. How was it that these repeated confessions were unavailing to obtain forgiveness, when David’s was? Because Saul only shrank from the punishment of his sin. David shrank in abhorrence from the sin itself (Psalms 51:4).