sharp knives: or, knives of flints, Before the use of iron was common, all the nations of the earth had their edge tools made of stones, flints, etc. Our ancestors had their arrows and spearheads made of flint; which are frequently turned up by the plough. And even when iron became more common, stone knives seem to have been preferred for making incisions in the human body. The Egyptians used such to open the bodies for embalming; and the tribe of Alnajab in Ethiopia, who follow the Mosaic institution, perform the rite of circumcision, according to Ludolf, cultris lapidibus:, with knives made of stone.
circumcise: Genesis 17:10-14; Deuteronomy 10:16, Deuteronomy 30:6; Romans 2:29, Romans 4:11; Colossians 2:11