Exodus 12:37-39

The Israelites traveled from Rameses to Succoth, about six hundred thousand able-bodied men on foot, besides their families. A mixed crowd also went up with them, along with a huge number of livestock, both flocks and herds. The people baked the dough they had brought out of Egypt into unleavened loaves, since it had no yeast; for when they were driven out of Egypt, they could not delay and had not prepared provisions for themselves.