1 Samuel 13:14

Also David was persecuted, as Jesus was persecuted. David was anointed by Samuel to be king instead of Saul who had sinned; and Jesus was anointed by John to be high priest instead of the priests, the ministers of the law. David was persecuted after his anointing; and Jesus was persecuted after his anointing. David reigned first over one tribe only and afterwards over all Israel; and Jesus reigned from the beginning over the few who believed on him, and in the end he will reign over all the world. Samuel anointed David when he was thirty years old; and Jesus when about thirty years old received the imposition of the hand from John. David wedded two daughters of the king; and Jesus wedded two daughters of kings, the congregation of the people and the congregation of the Gentiles. David repaid good to Saul his enemy; and Jesus taught, "Pray for your enemies." David was the heart of God; and Jesus was the Son of God. David received the kingdom of Saul his persecutor; and Jesus received the kingdom of Israel his persecutor. David wept with dirges over Saul his enemy when he died; and Jesus wept over Jerusalem, his persecutor, which was to be laid waste. David handed over the kingdom to Solomon and was gathered to his people; and Jesus handed over the keys to Simon and ascended and returned to him who sent him. For David's sake, sins were forgiven to his posterity; and for Jesus' sake sins are forgiven to the nations.

You ask, "Why did the Lord, undoubtedly having foreknowledge of the future, say 'I choose David according to my own heart,' although this very man committed such serious sins?" As a matter of fact, if we understand this statement concerning David himself, who was king of Israel after Saul had been condemned and slain, it was especially because God has foreknowledge of the future that he foresaw in him such great holiness and such true repentance, that he numbered him among those of whom he himself said, "Blessed are they whose iniquities are forgiven and whose sins are covered. Blessed is the one to whom the Lord has not imputed sin." Therefore, since God foreknew that he would sin and would wash his sins away by holy humility, why should he not say, "I have found David according to my own heart?" He was not going to impute sin to him who was doing so many good acts and living in such great holiness and by this same holiness offering the sacrifice of a contrite spirit for his sins. For all these reasons, it has very truthfully been said, "I have found David according to my heart." For, although the fact that he sinned was not according to God's heart, the fact that he atoned for his sins with a fitting penitence was according to God's heart. Only this, then, in him was not according to God's heart, which God did not impute [David's sins] to him. So, when this has been removed, that is, has not been imputed, what remains but that it be very truthfully said, "I have found David according to my own heart"?

In the same vein, take the words Samuel said to Saul.… These words are not to be taken to mean that God had intended for Saul himself to reign forever and subsequently had decided otherwise on account of Saul's sins (for God knew Saul was going to sin). They mean merely that God had planned for him to have such a kingdom as would typify an everlasting kingdom. Hence the added precision: "But your kingdom shall not continue."The kingdom which Saul's kingdom symbolized has continued and will continue—but not for Saul; for neither was he personally destined to rule forever, nor was even his progeny after him (at least in the sense of his blood successors following one after another) to make good the pledge "forever."

20. Behold how great were the things he lost, who, as he supposed, despised nothing. Behold, for seven days he waited for the prophet; but when he ceased to await him at the end of the day, he lost the glory of so great a dignity. Whence it is also said through the prophet: 'Woe to those who have lost patience' (Sirach 2:16). Indeed, those lose patience who do not bring to completion the good things they have begun.

20. Behold how great were the things he lost, who, as he supposed, despised nothing. Behold, for seven days he waited for the prophet; but when he ceased to await him at the end of the day, he lost the glory of so great a dignity. Whence it is also said through the prophet: 'Woe to those who have lost patience' (Sirach 2:16). Indeed, those lose patience who do not bring to completion the good things they have begun. To whom assuredly woe is pronounced: because they not only lose the reward of the labor they began, but are also struck with the punishment of their apostasy. Moreover, the punishment of the proud and disobedient king is declared when it is said: 'If you had not done this, the Lord would already have prepared your kingdom over Israel from now and forever; but it shall not stand.' From now and forever the kingdom is prepared for the elect: because those who rightly order temporal things prepare for themselves the height of eternal glory. Indeed, the kingdom of the elect is prepared now, when through divine grace their ministries are rightly administered. Which advances from now and forever: because from the lofty action of this present time, they merit that still loftier glory of eternity in heaven. And so finally it is said to the reprobate king: 'Your kingdom shall by no means stand any longer.' As if to say: Since he falls short of temporal righteousness, he does not attain to the height of eternity. Or for this reason it is said literally that it shall not stand: because it fell with him, and after him it did not remain in his sons. But, so that he may be struck with the punishment of envy, he is compelled to hear not only his own rejection, but also the election of another. For the prophet, continuing, says: (Verse 14) 'The Lord has sought for Himself a man after His own heart, and has commanded him to be leader over His people Israel.' 21. […]

But your kingdom shall not arise anymore. For every plant, He says, which My heavenly Father has not planted, shall be uprooted.

The Lord sought for Himself a man after His own heart, etc. Under the persona of David, he signifies Christ and the leaders of the Christian people; hence he specifically mentions his own people, and does not add Israel; so that even the Gentiles might …

"But was it not hard, to punish so little a sin so severely?" It was not little: disobedience to an express command, tho' in a small matter, is a great provocation. And indeed, there is no little sin, because there is no little God to sin against.

But now thy kingdom shall not continue,....

No, The Lord is righteous in all his ways and does no man any wrong, will be justified when he speaks and clear when he judges. By this, (1.) He shows that there is no sin little, because no little god to sin against; but that every sin is a forfeiture of the heavenly kingdom, for which we stood fair.

The Lord hath sought him a man after his own heart - That this man was David is sufficiently clear from the sequel. But in what sense was he a man after God’s own heart? Answer: 1. In his strict attention to the law and worship of God. 2. In his admitting, in the whole of his conduct, that God was King in Israel, and that he himself was but his vicegerent. 3. In never attempting to alter any of those laws, or in the least change the Israelitish constitution.

Saul said, Bring hither a burnt offering to me, and peace offerings--Saul, though patriotic enough in his own way, was more ambitious of gaining the glory of a triumph to himself than ascribing it to God.