תֵּ֭שֵׁב בְּאָחִ֣יךָ תְדַבֵּ֑ר בְּבֶֽן־אִ֝מְּךָ֗ תִּתֶּן־דֹּֽפִי׃
Sitzest du, da redest du gegen deinen Bruder, hängest dem Sohne deiner Mutter Makel an.
Rashi on Psalms
your mother’s son with whom you have no [legal] quarrel, since he does not inherit with you.
Rashi on Psalms
slander Heb. דפי, defamation to cast him off, an expression of (Num. 35:20): “he pushes him off (יהדפנו).”