1 Samuel 15:11

These texts declare that we should not cling stubbornly to our promises, but that they should be tempered by reason and judgment, that what is better should always be chosen and preferred and that we should pass over without any hesitation to whatever is proven to be more beneficial. This invaluable judgment also teaches us above all that, although each person's end may be known to God before he was born, he so disposes everything with order and reason and, so to say, human feelings, that he determines all things not by his power or in accordance with his ineffable foreknowledge but, based upon the deeds of human beings at the time, either rejects them or draws them or daily pours out grace upon them or turns them away.The choosing of Saul also demonstrates that this is so. Although, indeed, the foreknowledge of God could not be ignorant of his miserable end, he chose him from among many thousands of Israelites and anointed him king. In doing this he rewarded him for his deserving life at the time and did not take into consideration the sin of his future transgression. And so after he became reprobate, God as it were repented of his choice and complained of him with, so to speak, human words and feelings, saying, "I repent that I set up Saul as king, because he has forsaken me and not carried out my words." And again: "Samuel grieved over Saul, because the Lord repented that he had set up Saul as king over Israel."

Again, there are some things which are praiseworthy in people but cannot be present in God, such as shame, which is a prominent trapping of the state of sin, as is the fear of God. For not only in the Old Testament books is it praised, but the apostle also says, "perfecting holiness in the fear of God," none of which is to be found in God. Therefore, just as certain praiseworthy human qualities are not rightly predicated of God, so also are certain contemptible human qualities properly said to be in God, not as they are found in people but only in a very different manner and for different reasons. For shortly after the Lord had said to Samuel, "I repent that I have made Saul king," Samuel himself said of God to Saul: "He is not like a man, that he should repent." This clearly demonstrates that even though God said "I repent," it is not to be taken according to the human sense, as we have already argued at length.

7. He believed that he did not hear the words of the prophet, but the Lord complains that He has been abandoned, when He shows that His words have not been fulfilled in deed. Now the Lord speaks to the Church, saying: "He who hears you, hears me; and he who despises you, despises me" (Luke 10:16). Therefore, those who through disobedience depart from the word of preachers abandon the Lord, because they withdraw from those through whose ministry they are made present to the divine will. They do not then fulfill the words of the Lord in deed, because outwardly men speak, but inwardly God speaks in men. Therefore it is not they who speak, but the Holy Spirit (Matt. 10:20). In preachers, therefore, the outward lowliness of the flesh is not to be despised, whose minds the sublimity of the Godhead so graciously inhabits. What then does it mean that the Lord is said to repent, when He is not believed to be changed by emotions? But because supreme immutability speaks with mutable beings, after the manner of those with whom He speaks, when He is said to repent, it is indicated that the recklessness of the proud displeases Him. For we are accustomed to repent when those to whom we recall having bestowed honors or gifts repay us with evils. Because, therefore, almighty God complains after our manner about the ingratitude of the proud king, He is said to repent of having conferred royal dignity upon him. This is certainly said to the great increase of damnation for the proud: because what they are, they now are not for merit but for punishment, because they are not in the will of God. Therefore, for God to repent is to not have His will in the reprobate, when He remembers the honors He bestowed, but recognizes that those upon whom He conferred good things make evil use of the good things He conferred. […]

And Samuel was grieved, etc. These are not to be explained allegorically but rather are to be drawn to the imitation of virtue: so that for the errors of brothers, which they themselves cannot yet understand in themselves, we should not only be grieved in …

Repenteth - Repentance implies grief of heart, and change of counsels, and therefore cannot be in God: but it is ascribed to God when God alters his method of dealing, and treats a person as if be did indeed repent of the kindness he had shewed him. All night - To implore his pardoning mercy for Saul, and for the people. Is turned back - Therefore he did once follow God.