1 Samuel 10:1
Then Samuel took a vial of oil, and poured it upon his head, and kissed him, and said, Is it not because the LORD hath anointed thee to be captain over his inheritance? Then Samuel took a vial of oil, and poured it upon his head, and kissed him, and said, Is it not because the LORD hath anointed thee to be captain over his inheritance?
The anointing took place after Israel demanded a king, a demand that arose from dissatisfaction and pride, though the stated complaint was that Samuel's sons were unjust. Samuel poured oil on Saul's head to mark his divine appointment as captain and leader over Israel, the Lord's inheritance. Samuel's kiss accompanied the commissioning of Saul. Samuel's spoken words identified Saul's appointment as authorized by the Lord.
The exact signs Samuel foretold for Saul's journey were meant to confirm that divine authority, strengthen Saul's faith, and assure him that God's Spirit would qualify and equip him for the position. God did not leave Saul to face the responsibilities of kingship alone but promised that the Spirit would come upon him as guide and helper, change him, and enable him to prophesy. Saul received this appointment when he was little in his own sight and willing to be taught, and the Lord placed him where he could develop the qualities needed to rule.
God's call and help did not remove Saul's responsibility to obey the responsibilities God had laid on him. If Saul relied on his own judgment he would act impulsively and make serious errors, but if he stayed humble and sought divine wisdom, grace would strengthen his good qualities and weaken his faults.