Throughout the Bible we find God portrayed as a Father. There God is specifically called the Father of the nation of Israel ( Deut 32:6 ; Isa 63:16; 64:8 ; Jeremiah 3:4 Jeremiah 3:19 ; 31:9 ; Mal 1:6 ; 2:10 ) or the Father of certain individuals ( 2 Sam 7:14 I will be his father, and he will be my son. When he does wrong, I will punish him with a rod wielded by men, with floggings inflicted by human hands.
1 Chronicles 17:13 I will be his father, and he will be my son. I will never take my love away from him, as I took it away from your predecessor.
1 Chronicles 22:10 He is the one who will build a house for my Name. He will be my son, and I will be his father. And I will establish the throne of his kingdom over Israel forever.'
Psalm 89:26 He will call out to me, 'You are my Father, my God, the Rock my Savior.'
Jesus fulfilled the PROPHETS. Those scriptures are Jesus speaking about when he comes as a Son.
Matthew 5:17 "Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them.
Paul is quoting those scriptures.
Hebrews 1:5
For to which of the angels did God ever say, "You are my Son; today I have become your Father"? Or again, "I will be his Father, and he will be my Son"?
1 Chronicles 17:13
I will be his father, and he will be my son. I will never take my love away from him, as I took it away from your predecessor.
2 Samuel 7:14
I will be his father, and he will be my son. When he does wrong, I will punish him with a rod wielded by men, with floggings inflicted by human hands.
Acts 13:33
he has fulfilled for us, their children, by raising up Jesus. As it is written in the second Psalm: "'You are my son; today I have become your father.'
Hebrews 5:5
In the same way, Christ did not take on himself the glory of becoming a high priest. But God said to him, "You are my Son; today I have become your Father."
When your days are over and you go to be with your fathers, I will raise up your offspring to succeed you, one of your own sons, and I will establish his kingdom. He is the one who will build a house for me, and I will establish his throne forever. I will be his father, and he will be my son. I will never take my love away from him, as I took it away from your predecessor. I will set him over my house and my kingdom forever; his throne will be established forever. (1 Chronicles 17:11-14)
This prophecy has been said to have a double fulfillment. It is first fulfilled in Solomon, who built the temple, but he did what God forbade. Solomon amassed a great fortune and married foreign wives. His kingdom broke apart a few years after his death. However, the prophecy looks forward to a “Son of David” who would come, who would have a kingdom without end. This shows without any argument that it is about “son of David” and the coming Messianic King.