מדרש על שמואל ב 18:20

IV) Because [thus] the king's son is dead (II Samuel 18:20). The word thus is lacking, because of the evil of his deeds, for he sought to kill his father and cover up the matter, and came to fornicate with his father's concubines. Though Joab said because thus the king's son is dead, the word thus is suspended on the margin, because the king's son was killed for his wrongs, but thus can mean right as in rightly have the daughters of Ẓelopheḥad spoken (Numbers 27:7) or "what you are saying is right." (Genesis 44:10).