Ezekiel 22:2

וְאַתָּה בֶן אָדָם הֲתִשְׁפֹּט הֲתִשְׁפֹּט אֶת עִיר הַדָּמִים וְהוֹדַעְתָּהּ אֵת כָּל תּוֹעֲבוֹתֶיהָ

And you, son of man, will you judge? Will you judge the city of blood and let her know all her abominations?

“City of blood?” That’s a pretty harsh thing to call Jerusalem! The Daas Sofrim explains that things weren’t as bad as the name makes it sound. It’s just that Jerusalem is the Holy City, so it is held to a higher standard. Any act of bloodshed, no matter how isolated, is relatively more serious there than it would be elsewhere.