en_tn_condensed/psa/002/007.md

I will announce a decree of Yahweh. He

The person saying this is the king. This can be stated clearly. Alternate translation: "The king says, 'I will announce a decree of Yahweh.' He" (See: rc://en/ta/man/translate/figs-explicit)

He said to me

"Yahweh said to me"

You are my son! This day I have become your father

Among many peoples in that part of the world then, men could decide to legally adopt children, who would become their heirs. Here Yahweh adopts a man and makes him king of Israel. Alternate translation: "I make you my son. This day I have become your father" or "Now you are my son and am your father"