Reference for Makkot 18:19

בעבר הירדן תלת בארץ ישראל תלת אמר אביי בגלעד שכיחי רוצחים

Across the Jordan—three [cities]; in the land of Israel—three?! [How can such diverse sized populations need the same number of cities?] Abaye said: In Gilead [more generally a term for the other side of the Jordan], there were a lot of murderers.

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