"And all the men of Israel were gathered against the city" (Judges 20:11). We learned there: In Jerusalem people are trusted concerning consecrated food, and during a pilgrimage festival even concerning terumah [the priestly heave-offering]. From where is this derived? Rabbi Yehoshua ben Levi said: For the verse states, "And all the men of Israel were gathered against the city, united as one man" (Judges 20:11). Scripture thereby made them all into haverim [companions trusted in matters of purity and tithes].
All Israel Gathered as One and Made Trustworthy Together
Yalkut Shimoni on Nach 75:2
ויאסף כל איש ישראל אל העיר. תנן התם בירושלים נמאמין על הקדש ובשעת הרגל אף על התרומה. מה"מ אריב"ל דאמר קרא ויאסף כל ישראל אל העיר כאיש אחד חברים הכתוב עשאם כלם חברים: