“You have acted foolishly,” Samuel declared. “You have not kept the command that the LORD your God gave you; if you had, the LORD would have established your kingdom over Israel for all time.
Here is, I. Saul's offence in offering sacrifice before Samuel came. Samuel, when he anointed him, had ordered him to tarry for him seven days in Gilgal, promising that, at the end of those days, he would be sure to come to him, and both offer sacrifices for him and direct him what he should do. This we had Sa1 10:8.
Commenting on 1 Samuel 13:8-14
And Samuel said to Saul, thou hast done foolishly,.... Not by intruding himself into the priest's office, with that he is not charged, but not waiting the full time till Samuel came; which showed his impatience, disregard to Samuel, and distrust of God; and though he thought he had acted wisely, and taken the proper precautions in his circumstances, yet he acted foolishly; and though...
And Samuel said to Saul, Thou hast done foolishly: thou hast not kept the commandment of the LORD thy God, which he commanded thee: for now would the LORD have established thy kingdom upon Israel for ever. (i) Who willed you to obey him, and rest on the words spoken by his prophet.