Joshua 5:2 (KJV)

And it came to pass, when all the kings of the Amorites, which were on the side of Jordan westward, and all the kings of the Canaanites, which were by the sea, heard that the LORD had dried up the waters of Jordan from before the children of Israel, until we were passed over, that their heart melted, neither was there spirit in them any more, because of the children of Israel.

And Joshua made him sharp knives, and circumcised the children of Israel at the hill of the foreskins.

And this is the cause why Joshua did circumcise: All the people that came out of Egypt, that were males, even all the men of war, died in the wilderness by the way, after they came out of Egypt.

Now all the people that came out were circumcised: but all the people that were born in the wilderness by the way as they came forth out of Egypt, them they had not circumcised.

For the children of Israel walked forty years in the wilderness, till all the people that were men of war, which came out of Egypt, were consumed, because they obeyed not the voice of the LORD: unto whom the LORD sware that he would not shew them the land, which the LORD sware unto their fathers that he would give us, a land that floweth with milk and honey.

And their children, whom he raised up in their stead, them Joshua circumcised: for they were uncircumcised, because they had not circumcised them by the way.