Joshua 5:3-7

So Joshua made flint knives for himself, and circumcised the sons of Israel at the hill of the foreskins. And this is the reason why Joshua circumcised them: All the people who came out of Egypt who were males, all the men of war, had died in the wilderness on the way, after they had come out of Egypt. For all the people who came out had been circumcised, but all the people born in the wilderness, on the way as they came out of Egypt, had not been circumcised. For the children of Israel walked forty years in the wilderness, till all the people who were men of war, who came out of Egypt, were consumed, because they did not obey the voice of the LORD—to whom the LORD swore that He would not show them the land which the LORD had sworn to their fathers that He would give us, “a land flowing with milk and honey.” Then Joshua circumcised their sons whom He raised up in their place; for they were uncircumcised, because they had not been circumcised on the way.