2 Samuel 3:31
And David said to Joab, and to all the people that were with him, Rend your clothes, and gird you with sackcloth, and mourn before Abner. And king David himself followed the bier. And David said to Joab, and to all the people that were with him, Rend your clothes, and gird you with sackcloth, and mourn before Abner. And king David himself followed the bier.
Joab had treacherously murdered Abner, but David could not visit the crime with just retribution because the kingdom was still unsettled and Joab and his brother Abishai were powerful in position. David gave Abner a burial with public honors and required Joab, at the head of the army, together with all the people with him, to take part in the mourning services with torn garments and clothed in sackcloth. The command to mourn was David's public manifestation of his abhorrence of the murder. David himself showed his grief by keeping a fast on the day of burial and by following the bier as chief mourner. At the grave David then spoke an elegy over Abner that was a cutting rebuke of the murderers.