Jamieson, Fausset and Brown on 1 Chronicles 19:4-5

4-5. shaved them--not completely, but only the half of their face. This disrespect to the beard, and indecent exposure of their persons by their clothes being cut off from the girdle downwards, was the grossest indignity to which Jews, in common with all Orientals, could be subjected. No wonder that the men were ashamed to appear in public--that the king recommended them to remain in seclusion on the border till the mark of their disgrace had disappeared--and then they might, with propriety, return to the court.

1Ch 19:6-15. Joab and Abishai Overcome the Ammonites.