Albert Barnes Commentary 1 Samuel 15:13

"And Samuel came to Saul; and Saul said unto him, Blessed be thou of Jehovah: I have performed the commandment of Jehovah." — 1 Samuel 15:13 (ASV)

Since Gilgal was within 15 miles of Ramah, Samuel could have easily come from there that morning. Until now, self-will and rashness had been Saul’s chief faults. He now seems to add falsehood and hypocrisy.