Verse 31: Priests tried to avoid unnecessary impurity from corpses (touching a corpse rendered one unclean for seven days), even though this one is leaving Jerusalem, hence not about to serve in the temple. Some Jews went so far as to teach that one could contract impurity if so much as one’s shadow touched the corpse! Because this priest is heading (presumably home) to Jericho, where many wealthy priests lived, he might be a wealthy priest.
32: Levites sought to avoid ritual impurity, although the standards for them were less strict than for priests (see 10:31).
33: Because some Jewish stories involved a priest, a Levite, and an Israelite, some suggest that Jesus’ first audience may have expected him to mention a lay Israelite next. Jews and Samaritans were mutually hostile, and religious justified their respective nationalisms.
34: People used oil medicinally and for washing wounds; they could also use wine to disinfect wounds. Sources suggest that strict Jewish people avoided Gentile oil, so they may have done the same with Samaritan oil. A donkey might have seated both men, unless (as is very possible for a donkey-owner) the Samaritan was a merchant with many wares.
The Samaritan instead leads the donkey, taking the inferior (even servile) position to help the Israelite. The possible allusion to 2 Chronicles 28:15 and its context would remind Jesus’ most biblically literate hearers of a common bond uniting two different kingdoms in the land.
35: “I will repay” appears as a common formula in ancient documents about debts. Because inns were known for immorality and innkeepers often mistrusted, his promise to pay more offered the innkeeper further incentive to tend to the wounded man.
37: Although the legal expert is reluctant to simply confess, “the Samaritan,” Jesus has forced him to answer his own question offered in 10:29.
(Adapted from Dr. Keener’s personal research. Used with permission from InterVarsity Press, which published similar research by Dr. Keener in The IVP Bible Background Commentary: New Testament. Buy the book here.)