Joshua 5:2-5

2At that time the Lord told Joshua, “Make flint knives and circumcise this second generation of Israelites.”

3So Joshua made flint knives and circumcised the entire male population of Israel at Gibeath-haaraloth.

4Joshua had to circumcise them because all the men who were old enough to fight in battle when they left Egypt had died in the wilderness.

5Those who left Egypt had all been circumcised, but none of those born after the Exodus, during the years in the wilderness, had been circumcised.