אֲסַפְּרָ֗ה אֶֽ֫ל חֹ֥ק יְֽהוָ֗ה אָמַ֘ר אֵלַ֥י בְּנִ֥י אַ֑תָּה אֲ֝נִ֗י הַיּ֥וֹם יְלִדְתִּֽיךָ׃
I will tell of the decree: The LORD said unto me: 'Thou art My son, this day have I begotten thee.
Rashi on Psalms
I will tell of the decree Said David, “This is an established decree, and [one] that I have received to tell this and to make known.”
Radak on Psalms
Let me declare it for a decree: – This is the utterance of David, who says, I will make this declaration a decree and rule. And what is the declaration? That