'Certain' in the Bible

Now there came a time, in the days of the judges, when there was no food in the land. And a certain man went from Beth-lehem-judah, he and his wife and his two sons, to make a living-place in the country of Moab.

Now, in earlier times this was the way in Israel when property was taken over by a near relation, or when there was a change of owner. To make the exchange certain one man took off his shoe and gave it to the other; and this was a witness in Israel.