Exodus 12:37-39

37Now the Israelites journeyed from Rameses to Succoth, about six hundred thousand men on foot, besides [the women and] the children.

38A mixed multitude [of non-Israelites from foreign nations] also went with them, along with both flocks and herds, a very large number of livestock.

39And they baked unleavened cakes of the dough which they brought from Egypt; it was not leavened, since they were driven [quickly] from Egypt and could not delay, nor had they prepared any food for themselves.