Samuel said to Saul, Yahweh sent me to anoint you to be king over his people, over Israel: now therefore listen you to the voice of the words of Yahweh.
The fact is that all three chapters  (1 Samuel 13;  1 Samuel 14; and  1 Samuel 15) record successive instances of Saul's taking matters into his own hands and rejecting any restraint whatever upon his actions by what was obviously the will of God. Again, referring to  Jeremiah 18:7-10, no believer will find any fault whatever with what is written in these chapters.