mistreated: The same word appears in Exodus 1:11–12. Egypt, like "birds of prey" (Genesis 15:11), tried to destroy Israel and stop the fulfillment of the covenant.
four hundred years: This is probably an approximate number (also Acts 7:6; compare Exodus 12:40; Galatians 3:17). According to the Hebrew text's timeline, the family moved to Egypt around 1876 BC. The exodus happened around 1446 BC, but many scholars believe the Israelites left Egypt later, around 1270 BC (see Exodus Book Introduction, “The Date of the Exodus”).