Albert Barnes 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. Accidentally, or as it happened. It means that he did not do it with the intention to help the man who was wounded.

A certain priest. It is said that no fewer than twelve thousand priests and Levites lived in Jericho; and since their duties were in Jerusalem, of course, many of them would have been constantly traveling on that road.

When he saw him. He saw him lying, but did not come near him.

Passed by on the other side. On the farther side of the road. He did not even turn from his path to go and see him.