Jamieson, Fausset and Brown on 1 Samuel 15:24-26

24-26. I have sinned ... turn again with me, that I may worship the Lord--The erring, but proud and obstinate monarch was now humbled. He was conscience-smitten for the moment, but his confession proceeded not from sincere repentance, but from a sense of danger and desire of averting the sentence denounced against him. For the sake of public appearance, he besought Samuel not to allow their serious differences to transpire, but to join with him in a public act of worship. Under the influence of his painfully agitated feelings, he designed to offer sacrifice, partly to express his gratitude for the recent victory, and partly to implore mercy and a reversal of his doom. It was, from another angle, a politic scheme, that Samuel might be betrayed into a countenancing of his design in reserving the cattle for sacrificing. Samuel declined to accompany him.

I feared the people, and obeyed their voice--This was a different reason from the former he had assigned. It was the language of a man driven to extremities, and even had it been true, the principles expounded by Samuel showed that it could have been no extenuation of the offense. The prophet then pronounced the irreversible sentence of the rejection of Saul and his family. He was judicially cut off for his disobedience.