בנפל איבך אל תשמח
This refers to a Yid that one is permitted to consider an enemy (as in חמור שנאך). The fall of this goyte, a pathological liar, murderer, cheat, etc. is a true simcha for all of us. We, in golus, all deserve to view the מפלה of our enemies. That’s a major feature that made the miracle of קריעת ים סוף so great, as the posuk states וירא ישראל את מצרים מת על שפת הים. When המן was hung from a public display, the Yidden were in great simcha, ליהודים היתה אורה ושמחה וששון ויקר. Yes, we recognize seeing our enemies fall as a bit of wonderful news, and we should rejoice.