וַיֵּדְע֧וּ כָל־הָעָ֛ם וְכָל־יִשְׂרָאֵ֖ל בַּיּ֣וֹם הַה֑וּא כִּ֣י לֹ֤א הָיְתָה֙ מֵֽהַמֶּ֔לֶךְ לְהָמִ֖ית אֶת־אַבְנֵ֥ר בֶּן־נֵֽר׃ (פ)
So all the people and all Israel understood that day that it was not of the king to slay Abner the son of Ner.
Read midrashic interpretation of II Samuel 3:37: and classical rabbinic exegesis.