Exodus 12:37-42

37The Israelites journeyed from Rameses to Sukkoth. There were about six hundred thousand men on foot, besides women and children. 38Many other people went up with them, and also large droves of livestock, both flocks and herds.

39With the dough the Israelites had brought from Egypt, they baked loaves of unleavened bread. The dough was without yeast because they had been driven out of Egypt and did not have time to prepare food for themselves. 40Now the length of time the Israelite people lived in Egypt Masoretic Text; Samaritan Pentateuch and Septuagint Egypt and Canaan was 430 years. 41At the end of the 430 years, to the very day, all the LORD ’s divisions left Egypt.

42Because the LORD kept vigil that night to bring them out of Egypt, on this night all the Israelites are to keep vigil to honor the LORD for the generations to come.