וַיַּעַשׂ־ל֥וֹ יְהוֹשֻׁ֖עַ חַֽרְב֣וֹת צֻרִ֑ים וַיָּ֙מָל֙ אֶת־בְּנֵ֣י יִשְׂרָאֵ֔ל אֶל־גִּבְעַ֖ת הָעֲרָלֽוֹת׃
And Joshua made him knives of flint, and circumcised the children of Israel at Gibeath-ha-araloth.
Read kabbalistic (mystical) interpretation of Joshua 5:3: and classical mystical sources.