Foreseeing Sins And Penance

Quaeris enim, Quare dixerit Dominus, nimirum praescius futurorum, Elegi David secundum cor meum; cum talia tantaque ipse homo commiserit. Quod quidem, si de ipso David, qui reprobato Saüle et exstincto fuit rex Israël, dictum intelligamus; magis quia Deus praescius futurorum est, praevidit in eo tantam pietatem tamque veracem poenitentiam, ut esset in eorum numero de quibus ipse dicit: Beati quorum remissae sunt iniquitates, et quorum tecta sunt peccata. Beatus vir, cui non imputavit Dominus peccatum. Cum ergo praesciret eum Deus peccaturum, et peccata sua pia humilitate et sincera poenitentia deleturum, cur non diceret, Inveni David secundum cor meum; cui non erat imputaturus peccatum tam multa bona facienti, et cum tanta pietate viventi, et ipsa pietate pro peccatis suis sacrificium contriti spiritus offerenti? Propter haec omnia verissime dictum est, Inveni David secundum cor meum. Quia licet secundum cor Dei non esset, quod ille peccavit; tamen secundum cor Dei fuit, quod pro peccatis suis congrua poenitentia satisfecit. Hoc solum ergo in illo secundum cor Dei non fuit, quod illi Deus non imputavit. Hoc itaque ablato, id est non imputato, quid remansit, nisi unde verissime diceretur, Inveni David secundum cor meum? Sanctus Augustinus Hipponensi, Ad Dulcitium De Octo Quaestionibus Source: Migne PL 40.168

You ask why the Lord, who certainly can foresee the future, said, 'I have chosen David, a man according to my heart,' 1 when he would go on to commit such enormities. Because we should understand that which was said of David, who with Saul rejected and dead was king of Israel, was said more because the Lord who foresees the future foresaw in him such great piety and such true penitence that he was of the number of those of whom it is said, 'Blessed are those whose sins are forgiven and whose sins are covered. Blessed the man to whom the Lord does not impute sin.' 2 Therefore when the Lord foresaw him sinning and then his sins being wiped away with pious humility and sincere penitence, why should He not have said, 'I have chosen David, a man according to my heart,' that man to whom sin shall not be imputed so much as many good works, and who living with such great piety, with that same piety offered the sacrifice of a contrite spirit for his sins? 3 On account of this everything was spoken most truly with, 'I have chosen David, a man according to my heart.' He was according to the heart of the Lord not because he sinned, but he was according to the heart of God in that he offered the satisfaction of appropriate penance for his sins. Sin alone, therefore, was not in him according to the heart of God, and thus God did not impute it to him. Thus with sin washed away, that is, not to be imputed, what remained unless what was said most truly, 'I have chosen David, a man according to my heart?' Saint Augustine of Hippo, Concerning Eight Questions, To Dulcitius 1 1 Kings 13.14, Acts 13.22 2 Ps 31.1-2 3 Ps 50.19