'Knives' in the Bible

At that time Yahweh said to Joshua, "Make for yourself knives of flint, and circumcise the {Israelites} a second time."

So Joshua made knives of flint, and he circumcised the {Israelites} at the hill of the foreskins.

[There is] a generation whose teeth [are] swords, and its jawbones, knives, [in order] to devour the poor from the earth and the needy from humankind.