What historical event does the Lord use to motivate the Israelites?
Leviticus 19:34 (ESV)
34You shall treat the stranger who sojourns with you as the native among you, and you shall love him as yourself, for you were strangers in the land of Egypt: I am the LORD your God.
The Hebrews were originally sojourners in Egypt. However, during their time there, they were mistreated and became slaves. By loving sojourners, Israel would be distinct and holy.
34 You shall treat the stranger who sojourns with you as the native among you, and you shall love him as yourself, for you were strangers in the land of Egypt: I am the LORD your God.