Then came the word of the Lord unto Samuel,.... The word of prophecy, as the Targum; this came to him in a dream or vision, or by an articulate voice:
saying; as follows.

Repentance in God is not a change of mind, as it is in us, but a change of method. The change was in Saul; "He is turned back from following me." Hereby he made God his enemy. Samuel spent a whole night in pleading for Saul. The rejection of sinners is the grief of believers: God delights not in their death, nor should we. Saul boasts to Samuel of his obedience. Thus sinners think, by justifying themselves, to escape being judged of the Lord. The noise the cattle made, like the rust of the silver, James 5:3, witnessed against him. Many boast of obedience to the command of God; but what means then their indulgence of the flesh, their love of the world, their angry and unkind spirit, and their neglect of holy duties, which witness against them? See of what evil covetousness is the root; and see what is the sinfulness of sin, and notice that in it which above any thing else makes it evil in the sight of the Lord; it is disobedience: "Thou didst not obey the voice of the Lord." Carnal, deceitful hearts, like Saul, think to excuse themselves from God's commandments by what pleases themselves. It is hard to convince the children of disobedience. But humble, sincere, and conscientious obedience to the will of God, is more pleasing and acceptable to him than all burnt-offering and sacrifices. God is more glorified and self more denied, by obedience than by sacrifice. It is much easier to bring a bullock or lamb to be burned upon the altar, than to bring every high thought into obedience to God, and to make our will subject to his will. Those are unfit and unworthy to rule over men, who are not willing that God should rule over them.

GOD REJECTS HIS FOR DISOBEDIENCE. (1-Samuel 15:10-11)
Then came the word of the Lord unto Samuel, saying, It repenteth me that I have set up Saul--Repentance is attributed in Scripture to Him when bad men give Him cause to alter His course and method of procedure, and to treat them as if He did "repent" of kindness shown. To the heart of a man like Samuel, who was above all envious considerations, and really attached to the king, so painful an announcement moved all his pity and led him to pass a sleepless night of earnest intercession.

The word of the Lord came to Samuel: "It repenteth me that I have made Saul king, for he hath turned away from me, and not set up (carried out) my word." (On the repentance of God, see the remarks on Genesis 6:6.) That this does not express any changeableness in the divine nature, but simply the sorrow of the divine love at the rebellion of sinners, is evident enough from 1-Samuel 15:29. יי מאחרי שׁוּב, to turn round from following God, in order to go his own ways. This was Saul's real sin. He would no longer be the follower and servant of the Lord, but would be absolute ruler in Israel. Pride arising from the consciousness of his own strength, led him astray to break the command of God. What more God said to Samuel is not communicated here, because it could easily be gathered and supplied from what Samuel himself proceeded to do (see more particularly 1-Samuel 15:16.). In order to avoid repetitions, only the principal feature in the divine revelation is mentioned here, and the details are given fully afterwards in the account of the fulfilment of the instructions. Samuel was deeply agitated by this word of the Lord. "It burned (in) him," sc., wrath (אף, compare Genesis 31:36 with Genesis 30:2), not on account of the repentance to which God had given utterance at having raised up Saul as king, nor merely at Saul's disobedience, but at the frustration of the purpose of God in calling him to be king in consequence of his disobedience, from which he might justly dread the worst results in relation to the glory of Jehovah and his own prophetic labours.
(Note: "Many grave thoughts seem to have presented themselves at once to Samuel and disturbed his mind, when he reflected upon the dishonour which might be heaped upon the name of God, and the occasion which the rejection and deposition of Saul would furnish to wicked men for blaspheming God. For Saul had been anointed by the ministry of Samuel, and he had been chosen by God himself from all the people, and called by Him to the throne. If, therefore, he was nevertheless deposed, it seemed likely that so much would be detracted from the authority of Samuel and the confidence of the people in his teaching, and, moreover, that the worship of God would be overturned, and the greatest disturbance ensue; in fact, that universal confusion would burst upon the nation. These were probably the grounds upon which Samuel's great indignation rested." - Calvin.)
The opinion that ל יחר is also used to signify deep distress cannot be established from 2-Samuel 4:8. "And he cried to Jehovah the whole night," sc., praying for Saul to be forgiven. But it was in vain. This is evident from what follows, where Samuel maintains the cause of his God with strength and decision, after having wrestled with God in prayer.