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.
Bartenura
לפייס את העם – in order that they should know that it was not at the David’s advice that Joab should kill Avner [son of Ner, the military commander of Saul] (See 2 Samuel 3:37). And the Halakha is not according to Rabbi Yehuda.