Albert Barnes Commentary Ruth 4:2

"And he took ten men of the elders of the city, and said, Sit ye down here. And they sat down." — Ruth 4:2 (ASV)

Every city was governed by elders (Judges 8:14). For the number “ten,” compare Exodus 18:25. Probably the presence of at least ten elders was necessary to make a lawful public assembly, as among modern Jews ten (a minyan) are necessary to constitute a synagogue.