Clement of Rome

What shall we say of the celebrated David, to whom God said, "I have found a man after my own heart, David the son of Jesse, in eternal mercy I have anointed him." But even he says to God, "Have mercy on me, O God, according to your great mercy, and according to the multitude of your tender mercies blot out my iniquity. Wash me yet more from my iniquity, and cleanse me from my sin; for I knew my iniquity, and my sin is always before me."

1 Clement 18 ↗

Augustine of Hippo

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. …

City of God 17.6 ↗

Gregory the Dialogist

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. …

Commentary on 1 Kings, Book 5, Chapter 3 ↗

Bede

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 be shown to belong to this leader's command. However, the Lord did not seek as if He did not know, speaking to men in a human manner, even thus speaking, He seeks us. For the Son of Man came to seek and to save that which was lost (Luke 19). …

Commentary on Samuel ↗