A.T. Robertson Commentary Luke 10:31

"And by chance a certain priest was going down that way: and when he saw him, he passed by on the other side." — Luke 10:31 (ASV)

By chance (κατα συγκυριαν). Here only in the N.T., meaning rather, "by way of coincidence." It is a rare word elsewhere and in late writers like Hippocrates. It is from the verb συγκυρεω, though συγκυρησις is more common.

Was going down (κατεβαινεν). Imperfect active as in verse 30. Passed by on the other side (αντιπαρηλθεν). Second aorist active indicative of αντιπαρερχομα, a late double compound here (verses 31,32) only in the N.T., but in the papyri and late writers. It is the ingressive aorist (ηλθεν), came alongside (παρα), and then he stepped over to the opposite side (αντ) of the road to avoid ceremonial contamination with a stranger. A vivid and powerful picture of the vice of Jewish ceremonial cleanliness at the cost of moral principle and duty. The Levite in verse 32 behaved precisely as the priest had done and for the same reason.