I will be his Father, and he will be My son: The kings who came from David’s family had a special covenant relationship with God (a relationship based on God’s promises). This relationship was similar to the one God had with the whole nation of Israel (compare Exodus 6:7; Leviticus 26:12).
Jesus later became the fullest and final fulfillment of this promise (see Hebrews 1:5). Paul also quoted this statement and applied it to all believers (2 Corinthians 6:18).
When he does wrong, I will discipline him: God promised to correct and guide David’s descendants, the future kings of Israel, when they sinned. In this way, God would help them return to faithful obedience. Jesus never sinned, but he still experienced suffering and learned obedience through what he endured (see Hebrews 4:15; 5:8; 12:1–11).