Joshua 5:2-5

2At that time the LORD said to Joshua, “Make flint knives and circumcise the sons of Israel once again.1” 3So Joshua made flint knives and circumcised the sons of Israel at Gibeath-haaraloth.2

4Now this is why Joshua circumcised them: All those who came out of Egypt—all the men of war—had died on the journey in the wilderness after they had left Egypt. 5Though all who had come out were circumcised, none of those born in the wilderness on the journey from Egypt had been circumcised.