וַיֹּאמֶר֩ דָּוִ֨ד אֶל־יוֹאָ֜ב וְאֶל־כָּל־הָעָ֣ם אֲשֶׁר־אִתּ֗וֹ קִרְע֤וּ בִגְדֵיכֶם֙ וְחִגְר֣וּ שַׂקִּ֔ים וְסִפְד֖וּ לִפְנֵ֣י אַבְנֵ֑ר וְהַמֶּ֣לֶךְ דָּוִ֔ד הֹלֵ֖ךְ אַחֲרֵ֥י הַמִּטָּֽה׃
And David said to Joab, and to all the people that were with him: ‘Rend your clothes, and gird you with sackcloth, and wail before Abner.’ And king David followed the bier.
Read Kabbalistic (mystical) interpretations of II Samuel 3:31: Zohar and classical Jewish mystical sources, free online.