1 Samuel 15:4-6 (NLT2) "So Saul mobilized his army at Telaim. There were 200,000 soldiers from Israel and 10,000 men from Judah. Then Saul and his army went to a town of the Amalekites and lay in wait in the valley. Saul sent this warning to the Kenites: “Move away from where the Amalekites live, or you will die with them. For you showed kindness to all the people of Israel when they came up from Egypt.” So the Kenites packed up and left.
Here we see a compassionate side of King Saul. He knew that the Kenites were not in the order by God to be killed. So he let them go. Saul gets a bad rep because of his treatment of David and he should but there were some tender times in his life. Up to this point in his life, Saul had obeyed God but there is trouble ahead.