1 Samuel 13:14

A man after his own heart That is, such a man as will fulfil all the desires of his heart, and not oppose, them as thou dost. The Lord hath commanded That is, hath appointed, as the word commanded is often used. But although God threatened Saul with the loss of his kingdom for his sin, yet, it is not improbable, there was a tacit condition implied, namely, if he did not repent of this, and of all his sins; for the full, and final, and peremptory sentence of Saul's rejection is plainly ascribed to another cause, 1 Samuel 15:11; 1 Samuel 15:23; and, till that second offence, neither the Spirit of the Lord departed from him, nor was David anointed in his stead. But, “was not this a severe sentence now passed on Saul? Was it not hard to punish so little a sin with the loss of his kingdom?” Not to mention that no sin is little, because God, against whom all sin is committed, is a being of infinite majesty; and not to insist that what to men seems a small offence, to him, who knows the heart, may appear a heinous crime; this sin of Saul certainly can in no point of view be thought little, being an act of manifest disobedience to a known and express command of God; and disobedience to God, though in a small matter, is a great provocation. “Samuel expressly says, Thou hast not kept the commandment of the Lord thy God, which he commanded thee. What was this commandment? Why, not only to wait seven days till Samuel came to assist at the sacrifice, but to receive God's direction, by the prophet, what he should do, or what measures he was to take upon the invasion of the Philistines, and not to act in so critical a conjuncture without his orders. Saul, under a pretence of piety, and making supplication to the Lord, absolutely contradicts the command, thinks himself above waiting for the prophet, takes upon himself the ordinance of an affair that no way belonged to him; and, as though God's direction by the prophet was of no consequence to him, resolves to act for himself, and deal with the Philistines as well as he could. Let any inferior prince thus violate the orders of his sovereign, and act in any affair of importance directly contrary to his instructions and duty, and no one will scruple to pronounce him guilty of rebellion, or think he was too hardly treated by being removed from his dignity and government.” Dodd and Chandler.