https://www.btstories.com/sauls-disobedience/
One day Samuel went to Saul with instructions from God. “The Amalekites attacked my people when I brought them out of Egypt. Therefore, go to battle with them and destroy everything. Kill all the people and all of their livestock. Don’t leave anything alive.”
So Saul took his army and attacked the Amalekites. He defeated them, but didn’t kill everything. Saul’s men kept the best of the livestock for themselves. They also captured king Agag and didn’t kill him.