1 Chronicles 17:13
I will be his father, and he shall be my son: and I will not take my mercy away from him, as I took it from him that was before thee: I will be his father, and he shall be my son: and I will not take my mercy away from him, as I took it from him that was before thee:
The verse stands in God's answer to David concerning the temple, within the account of David's plan to build a house worthy of God. David first formed that plan and told it to the prophet Nathan, and God accepted David's good intentions yet refused him the honor of building, reserving that work for his son Solomon, David's successor, who was to build a house for God. The Chronicles account is parallel to the account in Samuel.
God promises David concerning his son and royal heir that He will be a father to him and he shall be His son, and that He will not take His mercy away from him as He took it from Saul, the king before David. The promise is that David's kingdom and throne shall be established forever, with God's faithfulness not failing despite the disobedience of his descendants and the punishment or temporary overthrow of their kingdom.
The promise of the enduring kingdom extends beyond Solomon and points to the Messiah and the everlasting rule of Christ. It belongs to Christ, not to Solomon, and is fulfilled in him, to whom belong the sure mercies of David, God being his Father and he being God's Son with mercy never taken away. Solomon's sad history proves such certainty could not exist if the seed were merely a human son of David.
The verse establishes Christ's status as the Son of God, giving Him a special right to the throne beyond His descent from David. He is David's son and heir, both Son of God and Son of man, and both son and Lord of David. Fulfillment is certain in Christ because, unlike Solomon, He remained faithful and overcame all the power and temptations of the enemy. He resisted temptation and the lure and glory of this world, endured and suffered hunger and thirst without complaining or presuming on His Father's compassion, and His sufferings, groans, tears and blood attest to and seal hope in Him.
The promise extends to David and to Israel, over whom Christ as David's heir was appointed to reign. For its human subjects, gathered from fallen sons of Adam liable to sin and to come short of grace, it is conditional, and obedience to God's law is the means to secure an interest in it and the condition its promises rest on. The same law underlies the covenant with Abraham, because Christ is both the seed of Abraham and heir to those promises and the son of David and heir to the throne. Believers are made partakers of both classes of promises by the same means and on the same conditions, so the promises to Abraham and David are received on the same terms.